ELI5: Explain Like I'm 5

Anti-virus

An anti-virus is a special kind of software that is designed to run on your computer and help protect it from nasty things like viruses, spyware, and other malicious programs. It works by scanning all of the files and programs that are installed on your computer and checking them to make sure they are safe. If it finds any suspicious files or programs, it will take steps to keep them from harming your computer.