Categories of Spyware : Trojan

What is a Trojan : It's a hacker tool that is secretly installed on your Pc and that allows the attacker to get almost complete over your computer.

Definition of Trojan :
In computers, a Trojan horse is a program in which malicious or harmful code is contained inside apparently harmless programming or data in such a way that it can get control and do its chosen form of damage, such as ruining the file allocation table on your hard disk.