A Trojan Horse, often referred to as just a Trojan, is a program which purports to do one thing, but actually does another.

Not always damaging or malicious, they are often associated with things like deleting files, overwriting hard-drives, or being used to provide remote access to a system for an attacker.

Classical Trojans include keyloggers being delivered as game files, or file deleters masquerading as useful utilities.

Trojans can be used for many purposes including

• Remote Access (sometimes called Remote Access Tools or RAT's, or Backdoors).

• Keylogging and password stealing (Most spyware falls into this category).