Human: What are the different types of computer viruses and how do they work? Assistant: 
The most common type of computer virus is a Trojan horse, which is designed to look like an innocuous program or file that appears harmless but actually contains malicious code. It can be used to gain control over your computer without your knowledge, allowing it to spread from one computer to another. Other types of computer viruses include worms, which replicate themselves across networks, and spyware, which monitors your activities online.