A Trojans or Trojan Horse is any programs that installs itself secretly, quite often with sinister intent. Once installed, the trojan author (hacker) can gain complete control of the infected PC. Trojans are usually designed to steal sensitive information and/or destroy the system. Trojans can be distributed as unsolicited email attachments, or bundled with freeware and shareware programs.
An apparently useful and innocent program containing additional hidden code which allows the unauthorized collection, exploitation, falsification, or destruction of data. When this program executes, the program performs a specific set of actions, usually working toward the goal of allowing the trojan to survive on a system and open up a backdoor.
