The keylogger is a spying tool that is used to obtain private information from a computer user.

Keyloggers have different functionalities depending upon their type but basically there are two types of keyloggers:

•    Keylogger software
•    Hardware based keyloggers

After installation the software keylogger saves all the information that is entered by the user to computer using a keyboard to a log file.

Keyloggers can then present this information to the attacker. Sophisticated keyloggers have the ability to send this information to remote server or even they can email that information to another person.

Keyloggers can store mouse gestures, web browsing history, cookies and can take snapshots of your screen. Keyloggers can also save a communication like chatting taking place between to users.

These keyloggers work in a stealth mode. and it is difficult to detect them. The keylogger can be activated by using specific sequence of keys to display the log file.

The hardware based keylogger works in the same way, the only difference is it comes as a device that is attached between the PS/2 or USB port and the keyboard.

The hardware based keylogger is more efficient and it does not require any installation, which makes it even more difficult for removal or detection.