Keyloggers are stealthy pieces of malware, designed to record any and all keyboard presses and secretly sending them to the cyber criminal.
Keyloggers usually don’t come with visible symptoms, since their main purpose is simply to collect sensitive information such as emails and passwords.
A keylogger is any piece of software or hardware that has the capability to intercept and record input from the keyboard of a compromised machine. The keylogger often has the ability to sit between the keyboard and the operating system and intercept all of the communications without the user’s knowledge. The keylogger can either store the recorded data locally on the compromised machine or, if it’s implemented as part of a larger attack toolkit with external communication capabilities, sent off to a remote PC controlled by the attacker. Although the term keylogger typically is used in relation to malicious tools, there are legitimate surveillance tools used by law enforcement agencies that have keylogging capabilities, as well.