Computer viruses

Computer viruses are also small pieces of software that attach themselves to real programs.

An example would be a virus that attaches itself onto windows explorer. Each time you run the program windows explorer the virus will also be executed and perform the function that it was meant to perform. This can be several things such as damaging files on your computer, or erasing them all together.

This is also the time in which the virus will try to spread itself onto other programs and even other computers!

Vir: https://www.microsoft.com/en-us/safety/pc-security/virus-whatis.aspx