What is a Virus?

A virus is a small executable file such as script that has the ability to self replicate its and spread from one PC to another. Viruses can pose from minor to severe security risks, such as data theft. Viruses enter user’s computer without user consent / permission with various objectives such as taking control of the computer, consuming CPU cycle, corrupting data, displaying annoying popup Windows, stealing information, spamming user contacts, keylogging with malicious intent, locking the desktop, falsely reporting problems with Windows to scare user into purchase a rogue programs, etc. there are a variety of  viruses such as Trojan, rootkit, spyware, Malware, keylogger, etc. Windows operating system are usually targeted by malware writers because more than 89% of all computers are Windows,  Mac OS operating system are far less affected–only 8 to 9% of the market share.