A computer program or a hardware device designed to record a user's keystrokes. It can either be a hardware device (installed on a keyboard) or a spyware software that causes every keystroke made on the computer to be recorded. The "keylogger" records everything the user types in, including e-mails, login names, passwords, credit card numbers, bank account Web sites, etc., in order to steal this information. Most keyloggers are invisible, they save the recorded keystrokes into a log file or send them to another machine.
Commercial keyloggers, both hardware and software, have existed for years. It was originally created as a diagnostic tool for software development. It is now used by the FBI (and others) to bypass security measures. Known as the computer virus that takes spying on victims to another level, this malicious program is capable of switching on a webcam for instance, allowing the author to literally peek into victims' lives!
This is kind of cyberfraud is an attempt to capture your personal information. Here's how the software version works: You click on a link to a Web site or open an attachment that secretly installs software on your computer. Once installed, it records everything you type. Thieves know how to retrieve this information, or even set it up to automatically have it sent back to them! This is a very real risk when using public or shared computers such as those in cybercafes.
To protect yourself, use the same anti-spyware software as listed in the spyware defintion!