Key Logger:
This is the most popular hacking tool kit to hackers. Mostly Black Hat Hackers and Gray Hat Hackers use this tool kit. They use this in wrong way. White Hat Hackers also use this tool kit but, they use this kit to find out the criminal. Basicaly this tool kit is a softwere which can be marged with anything. But, some of this tool kit is like a hardwere that means, it can be used by a physical structure like as Pendrive. There are two parts of a Key Logger.
This is just a simple infomation about keylogger. This is just for increasing knowledge.