Definition
A keylogger is a type of malicious software or hardware designed to record every keystroke a user makes on a computer. It operates by intercepting keyboard input, capturing everything from login credentials to sensitive personal information as it is typed. Understanding keyloggers is crucial for cybersecurity professionals to identify potential data breaches and protect user privacy. For instance, a keylogger could be installed on a public computer to steal credit card numbers entered during online transactions. Unlike a virus that might actively damage files, a keylogger's primary function is stealthy data exfiltration. This concept is fundamental in security domains and appears on certifications like CompTIA Security+ and CISSP.