Nmap (Network Mapper) is a free and open-source tool used for network discovery and security auditing. It helps users identify devices on a network, discover open ports, and detect services running on those ports. This information is crucial for network administrators and security professionals to assess the security posture of their systems. Originally developed by Gordon Lyon in 1997, Nmap has become a standard tool in the cybersecurity field. It supports various scanning techniques and can be used on multiple operating systems, including Windows, Linux, and macOS. Its versatility makes it valuable for both beginners and experienced users.