Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
Rinbot is a backdoor trojan which connects to a remote IRC channel and waits for commands. Remote IRC server can provide commands to download and execute malicious files.
This trojan drops and executes Kelvir.EB worm on the compromised computer.