What Is Trojan?
Trojans are malicious pieces of code used to install hacking software on a target system and aid the hacker in gaining and retaining access to that system. Trojans and their counterparts are important pieces of the hacker’s toolkit. Trojans is a program that appears to perform a desirable and necessary function but that, because of hidden and unauthorized code, performs functions unknown and unwanted by the user. Trojan generally consists of two parts: a client component and a server component. For the Trojan to function as a backdoor, the server component has to be installed on the victim’s machine.
Server is part of the Trojan on the Victim’s Computer. It opens a port in the Victim’s computer and invites the attacker to connect and administrate the computer.
Client Trojan is the part of the Trojan on the Attacker’s computer. It tries to connect the Victim computer and administrate the computer without the permission of the User.