Netstat is a command-line tool used to display network connections, routing tables, and various network interface statistics. It helps users monitor incoming and outgoing network traffic, providing insights into active connections and listening ports on a computer. This tool is commonly used for troubleshooting network issues and ensuring system security. By using Netstat, users can identify which applications are using network resources and detect any unauthorized connections. It can show information such as the local and remote IP addresses, port numbers, and the current state of each connection, making it a valuable resource for network administrators and security professionals.