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Based on the OCR Computer Science A-Level 2015 specification. Exam Board: OCR 3.1g - Pathfinding Specification: A-Level 2015 An instruction set is a list of all the instructions that a CPU can process as part of the FDE cycle . CPUs can have different sets of instructions that they can perform based on their function. The two most common instruction sets are the simpler RISC (Reduced Instruction Set Computer ) and more complicated CISC (Complex Instruction Set Computer ). Instruction Sets This page is still being updated. Graphical Processing Unit What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Q uesto's Q uestions 3.1g - Pathfinding: 1. What is cache memory ? [ 2 ] 3.1f - Searching Algorithms Theory Topics

Based on the OCR Computer Science A-Level 2015 specification. Exam Board: OCR 3.2a - Databases & Normalisation Specification: A-Level 2015 An instruction set is a list of all the instructions that a CPU can process as part of the FDE cycle . CPUs can have different sets of instructions that they can perform based on their function. The two most common instruction sets are the simpler RISC (Reduced Instruction Set Computer ) and more complicated CISC (Complex Instruction Set Computer ). Instruction Sets This page is still being updated. Graphical Processing Unit What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Q uesto's Q uestions 3.2a - Databases & Normalisation: 1. What is cache memory ? [ 2 ] 3.1b - Encryption & Hashing Theory Topics 3.2b - SQL

Based on the OCR Computer Science A-Level 2015 specification. Exam Board: OCR 2.4b: Assembly Language Specification: A-Level 2015 An instruction set is a list of all the instructions that a CPU can process as part of the FDE cycle . CPUs can have different sets of instructions that they can perform based on their function. The two most common instruction sets are the simpler RISC (Reduced Instruction Set Computer ) and more complicated CISC (Complex Instruction Set Computer ). Instruction Sets This page is still being updated. Graphical Processing Unit What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Q uesto's Q uestions 2.4b - Assembly Language: 1. What is cache memory ? [ 2 ] 2.4a - Programming & Pseudocode Theory Topics 2.4c - Object-Oriented Language

Based on the OCR Computer Science A-Level 2015 specification. Exam Board: OCR 4.3b - Flip Flops, Adders, Laws & Maps Specification: A-Level 2015 An instruction set is a list of all the instructions that a CPU can process as part of the FDE cycle . CPUs can have different sets of instructions that they can perform based on their function. The two most common instruction sets are the simpler RISC (Reduced Instruction Set Computer ) and more complicated CISC (Complex Instruction Set Computer ). Instruction Sets This page is still being updated. Graphical Processing Unit What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Multicore & Parallel Systems What is cache memory? Cache memory is temporary storage for frequently accessed data . Cache memory is very quick to access because it is closer to the CPU than other types of memory like RAM . Q uesto's Q uestions 4.3b - Flip Flops, Adders, Laws & Maps: 1. What is cache memory ? [ 2 ] 4.3a - Logical Operators & Truth Tables Theory Topics 5.1 - Computer Legislation

Learn how to use App Inventor 2 to create simple programs. Try to complete task 3 on this page. Perfect for Key Stage 3 students to experiment with block coding, objects and properties. App Inventor Task 3 - Munchin' Pizza This page will teach you how to make a simple app that changes pictures when a button is pressed . You can make the app more complex by adding sounds or additional buttons. Step 1: Set up App Inventor 2 Open App Inventor 2 (use the button on the right) and create a new project. You will need to log in with a Google account. Download the picture images from the zipped folder on the App Inventor 2 Basics page here . Once you have downloaded the pizza pictures you will need to upload them. Find the Media tab on the right side of App Inventor and click 'Upload File...' You will need to upload each picture individually. In the Palette tab on the left side, drag two buttons into the middle screen so they look like this: In the Components tab on the right, click on Button1 and click the Rename button at the bottom to change it to Pizza . Then Rename Button2 to Munch . This will help us when we code later as it will be less confusing. Click on the second button (Munch) that you just dragged into the centre then look in the Properties tab on the right and scroll down to Text . Change 'Text for Munch' to something like 'Munch Pizza' . Now click on the first button in the centre (Pizza) and in the Properties tab, click on Image and select the first image. It should be the full slice of pizza. When you have set the image, you might notice it goes a bit crazy. Still in the Properties tab, change the Height and Width to 'Fill parent...' for both. This will make the image fit within the boundaries of the screen. Finally, change the Text for the Pizza button to be blank. Otherwise it will appear on top of the pizza and look odd. So far you should have a button disguised as a pizza and another button that tells you to munch that lovely cheesy deliciousness. If your program does not look like this, read the instructions above again carefully. Step 2: Code Click on the Blocks button in the top right to start adding code. In the Blocks tab on the left side click on Munch and drag the when Munch Click block into the centre. This block will execute any code inside of it whenever the munch button is clicked. In the Blocks tab on the left side click on Logic and drag an if then block and snap it inside the block you just dragged over. Click on the blue cog button and drag four else if blocks inside the if block at the bottom. The blocks at the top will automatically update when you drag the blocks under the if block underneath. Because we are using different images, we need to check which image is currently being displayed, so we know which picture to change to. Firstly we want to check if the first image is being displayed. Connect an = block from the Logic section. Then add a Pizza Image block from the Pizza section. Lastly grab a " " block from the Text section and write the name of your first image inside (e.g. pizza1.jpg) Don't forget the extension (.jpg). But what does this code actually mean? It is checking to see what the current pizza image is. And if it is pizza1.jpg then it is going to... ...change the picture to pizza2.jpg, as if someone has munched the pizza! Grab a set Pizza Image to block from Pizza and then snap another " " block from Text and add the pizza2.jpg text inside. Now that we have written the code to check the current picture and move it to the next one when pressed, we just need to copy this for the other four pizza pictures. Rather than select all the blocks again, right-clicking on the blocks and selecting 'Duplicate' will copy them. Copy each block and then change the values so that if pizza2.jpg is the current image, then it sets it to pizza3.jpg and so on. Make sure that pizza5.jpg sets the image to pizza1.jpg so that it goes round in a loop. Program 3 Complete! Step 3: Run The easiest way to run an app that you have created at home using App Inventor 2 is to download the free MIT AI2 Companion App on your smartphone from the Google Play Store . At the top of the App inventor program on your computer , click on Connect and AI Companion . This will generate a six-digit code you can type into your phone. If your school has the emulator installed, you can also use this to test your app. Extra Step: Challenges 1. Create your own images and upload them . You can easily create your own set of pictures and link them together. Why not try: Eating a different type of food (e.g. cookie or doughnut). A simple scene that changes from night to day. A simple character that changes appearance (like Pikachu powering up a thunder strike with each button press). 2. Add a sound effect whenever a button is pressed . In the video at the top of the page, you'll see I have a 'munch' sound whenever the button is pressed. You could record this sound yourself or use a sound effect site. Once you have got your sound file (it should be short and .mp3) you need to upload it, just like you uploaded your images. In the Designer layout click 'Upload file...' in the Media tab on the right. Then look in the Palette tab on the left side, open the Media section and drag a Sound block into the centre. It will appear underneath the phone screen in a section called 'non-visible components' which is fine. Now click on Properties on the right side and choose the sound file you just uploaded in the Source box. Click on the Blocks button in the top right to start adding the code! In the Blocks tab on the left side, click on Sound1 and drag the call Sound1 Play block directly underneath when Munch click . This will play the sound everytime the button is pressed. 3. Add more buttons . You could add a second clickable button which reverses the pattern and a third button that resets the order back to the first image. Adding new buttons is easy - drag them from the Palette tab in the Designer layout. Change the button text in the Properties tab and the name of the button in the Components tab. To add code, click on Blocks in the top right then you can duplicate the code for Munch by right-clicking and choosing Duplicate. Now just change the values to what you want. If you are making a reset button, you don't need an if then statement, just set the image to your first image when the button is clicked. Keep messing around with the program and have fun! KS3 Home Tasks 4, 5 & 6

Learn about the six stages of compilation - lexical analysis, symbol table construction, syntax analysis, semantic analysis, code generation and code optimisation. Based on the 2020 Eduqas (WJEC) GCSE specification. 10.2: Stages of Compilation Exam Board: Eduqas / WJEC Specification: 2020 + A compiler translates source code (high-level language written by a programmer) into machine code in five separate stages : 1. Lexical Analysis The term 'lexical' refers to words and phrases . Source code needs to be broken down into tokens that can later be analysed. In lexical analysis: Spaces and comments are removed from the code. Identifiers , keywords and operators are replaced by tokens . A token is similar to a variable with a name and a value . A symbol table is created. T his table stores the addresses of all variables , labels and subroutines used in the program. 2. Syntax Analysis The term 'syntax' refers to sentence structure . In syntax analysis: The tokens created in the first stage are checked to see if they follow the syntax (spelling and grammar ) rules of the programming language. This process is called ' parsing ' . During parsing, if a syntax error is found then an error message is displayed and compilation stops . 3. Semantic Analysis The term 'semantic' refers to logic . Variables are checked in this stage to ensure they are used correctly: Variable checks ensure they are correctly declared and use a valid data type (for example integers are not assigned to decimal values). Operation checks ensure they are correct for the data type used ( for example dividing a number must result in an real value ). 4. Code Generation The machine code (data in a binary format ) is generated . 0010 1011 0101 0101 0110 0111 0101 0001 0101 0101 0101 0110 5. Code Optimisation The code is optimised so it is fast , efficient and uses as little of the computer's resources as possible. Q uesto's Q uestions 10.2 - Stages of Compilation: 1 a. List the 6 stages of compilation in order . [6 ] 1b. Create a poster or flowchart describing each of the 6 stages of compilation : 1. Lexical Analysis 2. Symbol Table Creation 3. Syntax Analysis 4. Semantic Analysis 5. Code Generation 6. Code Optimisation [ 10 total ] 10.1 - Translators Theory Topics 10.3 - Programming Errors

Learn how to easily embed a video from YouTube into an HTML web page. 8. Videos HTML Guide Watch on YouTube: Embedding a video from YouTube into your web page is very easy. YouTube Videos Find an appropriate video on YouTube and click the Share button underneath the video. Next, click the Embed option. Embed a video onto your web page. Copy the HTML code that is displayed on your screen and paste it directly into your HTML document. Next you can customise your web page with a background colour and different font styles. 7. Head Tags HTML Guide 9. Colours & Fonts

Learn about the main character sets - ASCII (American Standard Code for Information Interchange) and Unicode. Based on the J277 OCR GCSE Computer Science specification (first taught from 2020 onwards). 2.4b: Character Storage Exam Board: OCR Specification: J277 What is a Character Set? A character set is a table that matches together a character and a binary value . Each character in a character set has a unique binary number matched with it . Character sets are necessary as they allow computers to exchange data and humans to input characters . Two common character sets are ASCII and Unicode : H = 01001000 ASCII Unicode ASCII (American Standard Code for Information Interchange ) is a common character set which does not take up much memory space . It is important to understand that the number of characters that can be stored is limited by the bits available - ASCII uses 1 byte (8 bits ) which only gives 256 possible characters . This is enough for the English language but it can’t be used for other languages or all punctuation symbols. Unicode is a more popular character set because it uses 2 bytes (16 bits ) that allow for 65,536 possible characters . The extra byte allows many different languages to be represented , as well as thousands of symbols and emojis . However Unicode requires more memory to store each character than ASCII as it uses an extra byte . Character sets are logically ordered . For example, the binary code for A is 01000001 , B is 01000010 and C is 01000011 as the code increases by 1 with each character. The file size of a text file is calculated as shown below: bits per character x number of characters Example: A small text file uses the ASCII character set (which uses 8 bits per character ). There are 300 characters in the file . 300 x 8 = 2,400 bits This could be simplified as 300 bytes or 0.3 kilobytes . Q uesto's Q uestions 2.4b - Character Storage: 1. What is a character set and why are they needed ? [ 2 ] 2. Describe 3 differences between ASCII and Unicode . [6 ] 3. The binary code for the character P in ASCII is 01010000 . State what the binary code for the character S would be. [1 ] 4a. A text file uses the ASCII character set and contains 400 characters . What would the file size be in kilobytes ? [ 2 ] 4b. A text file uses the Unicode character set and contains 150 characters . What would the file size be in kilobytes ? [ 2 ] File Size of Text Files 01101010 = 256 possible characters 8 bits (1 byte) 1000101101001111 = 65,536 possible characters 16 bits (2 bytes) 2.4a - Number Storage Theory Topics 2.4c - Image Storage

Learn how to use time commands to display the current date and time in Python. Try practice tasks and learn through text and images. Perfect for students learning GCSE Computer Science in UK schools. top Python 5c - Time & Date ctime() The easiest way to output the current time and date is to use the ctime() command. Import the ctime command from the time library before you use and print it: from time import ctime print ( "Current time:" , ctime()) = Current time: Wed Sep 13 16:07:20 2023 This will print the time and date, but it looks rather unprofessional, and the exact format depends on the type of system that you are currently running so it may vary for different users. Date / Time Task 1 ( Dentist Surgery) Print a greeting for a dentist surgery with the current date and time. Example solution: Welcome to Greenvale Dentist Surgery, it is currently: Wed Sep 13 16:16:24 2023 strftime() A better alternative to the ctime() command is to use strftime() which stands for str ing f rom time as you can select specific parts of the date and time to display. This command requires a directive to be written with a percentage symbol as a string in the brackets . For example, the current hour (%H ), minute (%M ) and second (%S ) can be printed between colons to show the time . from time import strftime print ( "The current time is" , strftime( "%H:%M:%S" )) = The current time is 13:18:57 There are many different directives that you can use to display exactly what you are looking for, such as: from time import strftime day = strftime( "%A" ) print ( "The current day is" , day) month = strftime( "%B" ) print ( "The current month is" , month) year = strftime( "%Y" ) print ( "The current year is" , year) = The current day is Thursday The current month is September The current year is 2023 The following directives can be used with strftime(). Don't forget that directives must be typed within speech marks . Date - Weekday: %a – Current day of the week abbreviated (e.g. Sun, Mon) %A – Current day of the week in full (e.g. Sunday, Monday) %w – Current day of the week in chronological order (0 is Sunday and 6 is Saturday) %W – Current week number (e.g. 01, 26, 52) Month: %d – Current day of the month (e.g. 01, 11, 31) %m – Current month as a number (e.g. 01, 06, 12) %b – Current month abbreviated (e.g. Jan, Jun, Dec) %B – Current month in full (e.g. January, December) Year: %y – Current year abbreviated (e.g. 16, 17) %Y – Current year in full (e.g. 2016, 2017) %j – Current day of the year (e.g. 001, 150, 365) Time - Hour: %H – Current hour in 24-hour clock (e.g. 00, 12, 20) %I – Current hour in 12-hour clock (e.g. 01, 08, 12) %p – Whether it is currently AM or PM Minute: %M – Current minute (e.g. 00, 30, 59) Second: %S – Current second (e.g. 00, 30, 59) More Directives - %z – Current time difference from UTC (Co-ordinated Universal Time) (e.g. +0000, -0500, +1100) %Z – Current time zone (e.g. GMT Standard Time, EST, CST) Just looking for a quick date or time display and not bothered about customisation? Try these: %c – Current date and time in full (e.g. Tue Feb 19 13:35:20 2016) %x – Current date (e.g. 19/02/16) %X – Current time (13:36:20) Date / Time Task 2 ( Calendar App ) Create a program that asks the user if they want to see the current date , the current time or 'other '. Use the strfftime directives above to show what the user asks for. It's up to you which directives you use for the 'other' option , such as displaying the current day of the year (%j ) or current week of the year (%W ). Example solutions: Type TIME for the current time, DATE for the current date or OTHER: TIME The current time is 13:46PM Type TIME for the current time, DATE for the current date or OTHER: DATE The date today is Thursday 14 September 2023 Type TIME for the current time, DATE for the current date or OTHER: OTHER Did you know today is day number 257 of 2023? Between Dates You may want to work out the number of days between two dates . This can be done by importing the date command from the timedate library. Below is a simple example: from datetime import date date1 = date(2021,9,15) date2 = date(2022,1,20) difference = date2 - date1 print ( "There are" , difference.days , "days between" , date1 , "and" , date2) Make sure the date is entered in the format of year, month, day . The .days code removes the difference in hours and seconds to just display the number of days difference. There are 127 days between 2021-09-15 and 2022-01-20 Today's Date The program here uses strftime to check the current year, month and day and organise it into the date format . This can then be used together with code similar to the program above to check the number of days between one specific date and the current date. from datetime import date from time import strftime thisyear = int (strftime( "%Y" )) thismonth = int (strftime( "%m" )) thisday = int (strftime( "%d" )) todaysdate = date(thisyear,thismonth,thisday) print ( "The date today is" , todaysdate ) The date today is 2023-09-14 Input a Date The program here shows how to input a date into a format that can then be used by Python to work out the difference between two dates . from datetime import date year = int ( input ( "Enter a year: " ) month = int ( input ( "Enter a month: " ) day = int ( input ( "Enter a day: " ) chosendate = date(year,month,day) print ( "The chosen date is" , chosendate ) Enter a year: 1964 Enter a month: 5 Enter a day: 13 The chosen date is 1964-05-13 Date / Time Task 3 ( Days Alive) Create a program that works out how long the user has been alive for . Use the examples above to automatically make today's date and then allow the user to input their year , month and day of birth. Get Python to work out the difference between today and their date of birth. Example solutions: Enter a year: 1998 Enter a month: 3 Enter a day: 29 You have been alive for 9300 days! Enter a year: 2007 Enter a month: 12 Enter a day: 25 You have been alive for 5742 days! ⬅ 5b - Sleep 5d - Colorama ➡

Learn about ways to measure the success of protection. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 6.4 - Protection Measures Exam Board: OCR Specification: 2016 - Unit 2 Staff Responsibilities It is the staff of an organisation that will spend the most time handling and amending data so the company must have sufficient and effective protection measures in place so that staff are confident in their role and know their responsibilities of information security. Certain staff members may be responsible for types of data within an organisation, such as personal and confidential data. Clearly assigning specific people to roles ensures that they know what their job is and that they are responsible if data is lost. Organisations also need to carefully consider which members of staff have access rights to certain information. If data is sensitive or confidential then the more people that have access to that data , the higher the risk of it being lost or tampered with (accidentally or on purpose). Sensitive data should only be handled and accessed by those who need to use it as part of their job role to limit the chance of data loss. Staff should be trained so that they know how to adequately handle information including basic data security techniques and how to protect data from unauthorised access and loss. Disaster & Recovery Planning With important data often stored on a computer network, it is absolutely vital that a detailed and effective disaster recovery policy is in place in the event of data being lost due to an unexpected disaster. Disasters include natural disasters (e.g. fire, flood, lightning), hardware failure (e.g. power supply unit failing), software failure (e.g. virus damage) and malicious damage (e.g. hacking). There are three clear parts to a disaster recovery policy: Before the disaster: All of the possible risks should be analysed to spot if there are any weaknesses in preparation. Preventative measures should be taken after the analysis, such as making rooms flood-proof or storing important data at a different location . Staff training should take place to inform employees what should happen in the event of a disaster. During the disaster: The staff response is very important – employees should follow their training and ensure that data is protected and appropriate measures are put in place. Contingency plans should be implemented while the disaster is taking place, such as uploading recent data to cloud storage or securing backups in a safe room and using alternative equipment until the disaster is over. After the disaster: Recovery measures should be followed, such as using backups to repopulate computer systems. Replacement hardware needs to be purchased for equipment that is corrupted or destroyed. Software needs to be reinstalled on the new hardware. Disaster recovery policies should also be updated and improved . Assessment and Effectiveness Organisations should conduct information security risk assessments periodically to ensure that their physical and logical measures are up-to-date and that they provide the most effective methods of protection. There may be training drills of what should happen if a disaster or substantial data loss occurs so that the company is prepared . By testing the security measures in place, they can identify any weak-points and fix those highlighted vulnerabilities to minimise the possibility of external and internal data intrusion. As part of an organisation's security assessment, they may identify specific cost impacts . These are necessary financial expenditures to ensure the security of data and systems, such as: Software - e.g. security software such as firewalls may be purchased to protect networked systems. Hardware - e.g. buying secure storage devices and new computer systems. Training - e.g. hiring industry experts to train staff on how to keep data secure. Security - e.g. hiring staff to protect server rooms. Q uesto's Q uestions 6.4 - Protection Measures: 1. Describe why staff are so important when it comes to data protection . [3 ] 2. Explain the steps an organisation should take as part of a disaster recovery plan . Split your answer into before, during and after the disaster. [12 ] 3. Why is it important to conduct information security risk assessments ? [2 ] 4. Describe two cost impacts to a bank of keeping customer data secure. [4 ] 6.3 - Impacts Topic List 6.5 - Physical Protection

Learn about the three principles of information security - confidentially, integrity and availability. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 6.1 - Security Principles Exam Board: OCR Specification: 2016 - Unit 2 There are three key principles of data security that are protected in legislation such as the Data Protection Act (2018 ). Organisations storing personal or sensitive information must ensure that these three principles are upheld at all times . Confidentiality What it means: Information should only be accessed by individuals or groups with the authorisation to do so. How to uphold this principle: An organisation should use protection measures like usernames and passwords to ensure that only authorised people can access the sensitive data. Tiered levels of access or permissions can also limit who has access to the data. Integrity What it means: Information is maintained so that it is up-to-date , correct and fit for purpose . How to uphold this principle: Organisations should carry out regular data maintenance to update information (e.g. confirm contact details once a year). If storing data in a spreadsheet or database, record-locking should be used so that only person can edit at a time, preventing the data from becoming incorrect. Availability What it means: Information is available to the individuals or groups that need to use it. It should only be available to those who are authorised . How to uphold this principle: Staff should have the correct privileges so that they can easily access data when required. Data could be stored online , e.g. cloud storage so that it is available remotely using an internet connection. Data must also be kept safe from unauthorised access . Staff should not make additional copies of information which could be lost or stolen. Q uesto's Q uestions 6.1 - Security Principles: 1a. Describe what is meant by ' confidentiality ' . [1 ] 1b. Explain two ways that an organisation can keep data confidential . [4 ] 2a. Describe what is meant by ' integrity ' . [1 ] 2b. Explain two ways that an organisation can preserve the integrity of its data . [4 ] 3a. Describe what is meant by ' availability ' . [2 ] 3b. Explain two ways that an organisation can keep its data available . [4 ] 5.2 - Data Flow Diagrams Topic List 6.2 - Risks

Learn about different forms of malware including virus, worm and trojan. Learn about the different ways that malware can infect a computer system. Malware Malware is any type of harmful program that seeks to damage or gain unauthorised access to your computer system. Part 1: SiX Types of Malware Virus A virus can replicate itself and spread from system to system by attaching itself to infected files . A virus is only activated when opened by a human . Once activated, a virus can change data or corrupt a system so that it stops working . Trojan A trojan is a harmful program that looks like legitimate software so users are tricked into installing it . A trojan secretly gives the attacker backdoor access to the system . Trojans do not self replicate or infect other files. Ransomware Ransomware locks files on a computer system using encryption so that a user can no longer access them. The attacker demands money from the victim to decrypt (unlock) the data . ? ? Attackers usually use digital currencies like bitcoin which makes it hard to trace them. Spyware Spyware secretly records the activities of a user on a computer. The main aim of spyware is to record usernames, passwords and credit card information . All recorded information is secretly passed back to the attacker to use. Keylogger A keylogger secretly records the key presses of a user on a computer. Data is stored or sent back to the attacker. The main aim of a keylogger is to record usernames, passwords and credit card information . Keyloggers can be downloaded or plugged into the USB port . Worm A worm can replicate itself and spread from system to system by finding weaknesses in software . A worm does not need an infected file or human interaction to spread. A worm can spread very quickly across a network once it has infiltrated it. Part 2: Four ways malware cAN infect your system 1. A ccidentally downloading an infected file from an insecure website . 2. Phishing emails - clicking on attachments or links in spam emails . 3. Installing malware from a physical device, e.g. USB stick . 4. Self-replicating malware , such as worms , spreading across a network . Phishing & Staying Safe