Music and speech vary continuously in frequency and amplitude. In the same way, analogue signals can vary in frequency, amplitude, or both. You may have heard of FM and AM radio - Frequency Modulated radio and Amplitude Modulated radio. The diagram shows a typical oscilloscope trace of an analogue signal. 

Digital signals are a series of pulses consisting of just two states: ON (1) or OFF (0). There are no values in between. DAB radio is Digital Audio Broadcast radio - it is transmitted as digital signals. The diagram shows a typical oscilloscope trace of a digital signal. 

- Google Chrome
- Mozilla Firefox
- Internet Explorer
- Microsoft Edge
- Safari

- Google Chrome (www.google.co.uk)

- Google Chrome (www.google.com)

- Google Chrome (www.google.com)

- A plug in is typically a third-party software rather than the developer of the browser and are either called "add-ons" or "extensions". These are used as toolbars and support a wide range of graphics, animation, audio and video formats.

- They affect the performance by slowing down the rate at which the browser will load up. The more plug-ins you have, the more work the processor is required to do for it to load.

- CryptoLocker - This was a form of trojan horse ransomware which targeted Windows based PCs. It spread through various different methods such as email. Once a pc is infected, it would encrypt certain files within the hard drive or any mounted storage connected to the pc using RSA public key cryptography.
- ILOVEYOU - This virus costed a total of $10 billion worth of damage. 10% of the world's internet-connected pcs were believed to be have been infected. The infection was so severe that the goverment and some large corporations took their mailing system offline to aid with preventing the infection. Created by two Filipino programmers, once the .txt file was clicked onto, it would download itself onto and would send everyone within the user's mailing list and would proceed to overwrite files with itself making the pc unbootable.
- Zeus - Trojan horse made to infect Windows PC with the intention of performing various criminal tasks. The most common was usually the man-in-the-browser keylogging and form grabbing.
- MyDoom - This was a worm for Windows based PCs which became one of the fastes spreading email worm since the ILOVEYOU virus. The worm spreads by itself by appearing as an email transmission error which contains an attachment of itself. Once the worm is executed, it will sent itself to email addresses within the user's contact list and copies itself to any P2P(Peer To Peer) programs' folder to propagate itself throughout that network. The main program itself, opens a backdoor to allow remote access and it then launches a DOS attack on the SCO Group. The damage caused by this worm was around $38.5 Billion and is still active to this day.

What were they set up to do?
- Most malwares are made for the purpose of malicious intent. Either it be corruption of files and damage, accessing private data, ransom, personal gain and others.
What is a key-logger?
- A key-logger is a type of monitoring software which reveals every click and touch, conversation and download. This is a software which tracks/logs the keystrokes the user has used on their keyboard. This is done with malicious intent as this would allow the attacker see information such as your username or password, credit car numbers and many others.
What is a polymorphic virus?
- This is a complicated virus which affects data types and functions. This is a self-encrypted virus designed with the purpose of avoiding detection by a scanner. As infection occurs, the virus duplicates itself by creating usable or slightly modified versions of itself. To be able to remove polymorphic viruses would require the programmers to rewrite language strings which can be complex, time-consuming and costly.