What is Virus, Spyware and Cookies?

Virus:  Viruses are small programs written so that they can jump from one computer to another via
disk or network, which can cause disruption or damage to the computer system.

Spyware:  Spyware is a software that installs itself on computer and then spies on the computer
activity of the user.

Cookies:  Cookies are hidden information about  the user saved in the hard disc in the text file
format. Cookies personalizes the relationship of the user with the visited website.