Keystroke Logging

Keystroke logging, often referred to as keylogging, is the action of recording the keys struck on a keyboard, so that the person using the keyboard is unaware that their actions are being monitored. It also has very legitimate uses in studies of human-computer interaction. There are numerous keylogging methods, ranging from hardware and software-based approaches to acoustic analysis.

There are many counter measures for key logging such as One Time Passwords (OTP's), Anti Keylogger Softwares etc. For more information on this topic click on the above link.