Key Logger

Any program that records keystrokes is, technically, a key logger. The term tends to be used in malware circles for programs that surreptitiously record keystrokes and then make the log of keyboard activity available to someone other than the logged user(s). Commonly these log files are e-mailed to the person who planted the logging software, but on public access machines (in cyber-cafes, school and university computer labs, etc) that level of sophistication is not necessary as the ´attacker´ can simply access the log file from the compromised machine at a later date, revealing usernames and passwords for accessing other systems and other potentially sensitive information. Although more common in Trojan Horse programs and remote access Trojans, key loggers are sometimes used in the payloads of viruses.