1.1. a malicious program designed to replicate itself and transfer from one computer to another.
2. Worm
2.1. a malicious program that transfers from one computer to another by any types of means.
3. Trojan
3.1. a malicious program that disguises as a useful program but once downloaded or installed, leaves your PC unprotected and allows hackers to get your information.
4. Spyware
4.1. a program that runs in the background without you knowing it. It has the ability to monitor what you are currently doing and typing through keylogging.
5. Adware
5.1. a program designed to send you advertisement, mostly as pop-ups.
