There are many ways in which an attacker can attempt to break into or disrupt your computer. We are all familiar with computer viruses, which can be transmitted via email attachments or physical media. But once a computer is connected to broadband and thus often has a fixed identity on the Internet, it is much more vulnerable to a wider range of attacks.

In this section we'll look at some of the categories of malware, or malicious software, that may be used to attack your computer. Remember that some malicious software may blend two or more of these methods of attack.