Trojan horses are programs that pretend to be legitimate software, but actually carry out hidden, harmful functions.
Trojan horse is an umbrella term under which many types of malware sits: bots, backdoor Trojans and downloader Trojans.
A significant percentage of today’s malware is Trojans.
A Trojan program claims to have one function-and may even appear to carry it out-but actually does something different, usually without your knowledge. Trojans are often distributed with pirated software applications and keygens that create illegal license codes for downloadable software.