Keyloggers are one of the most dangerous spyware parasites.

Activity of these usually small malicious programs is really catastrophic. Although keyloggers do not destroy the operating system or installed software and don't corrupt files, they steal the most valuable user information, including all the passwords, login names, everything written in priceless documents, every letter in a chat conversation or e-mail message.

A typical keylogger not only records all keystrokes, but also captures screenshots of user activity, logs software usage, exact addresses of visited web sites, even mouse clicks and time when the user turns off his computer and sends all quietly sends gathered data to a predefined e-mail address. What can be worse? Keyloggers allow the attacker to be well informed about all your secrets, current works, contacts, interests, your entire life. However, you can prevent such an intervention. In most cases keystroke capture can be revealed and avoided. In this article I will give you several advices that you should always keep in mind.

Depending upon the nature of the information gathered, each piece of spyware may function differently. Some spyware applications simply gather information about a user's surfing habits, purely for marketing purposes, while others are far more malicious. In any case, the spyware attempts to uniquely identify the information sent across a network by using a unique identifier, such as a cookie on the user's hard disk or a Globally Unique Identifier (GUID). [ref 2] The spyware then sends the logs directly to a remote user or a sever that is collecting this information. The collected information typically includes the infected user's hostname, IP address, and GUID, along with various login names, passwords and other keystrokes. " Full article "