Hacking means gaining access and then controlling a computer or a network to perform certain actions that are not authorized or legally permitted by the legitimate owner of computer.

Hacking can be done for many purposes like industrial espionage, identity theft, cyber crime, for stealing confidential information or using a computer for an illegal purpose.

The hacking mechanism is complex and many techniques are used to accomplish the task. First a hacker has to gain access to the victim’s computer.

This is usually done by creating a backdoor access through Trojan attack or by stealing login id and password through a worm or spyware.

After gaining access the hacker may do what ever he like to do with the users computer. He can control the computer, store files or can use that computer as a bot to launch further complex and sophisticated attacks on targets.

Computer hacking is mostly common in teenagers. Apart from computer hacking there are many other forms of hacking like website hacking and user id hacking. Depending upon the purpose of hacking, hackers are categorized into many groups like:
•    Neophyte
•    Script kiddie
•    Hacktivist