Keystroke logging is making a record of each key that is pressed. Keystroke logging can be used to measure employee activity. Hackers can also use keystroke logging to get private information, such as passwords. This can be done using either putting a piece of hardware in the keyboard or on the cable; puttting a peice of software inside the computer; or, if the person being hacked is using a wireless keyboard, it's especially easy for the hacker to also detect the wireless signals.