tcpdump is a command-line packet analyzer tool used to capture and display network traffic. It allows users to monitor and analyze the data packets that flow through a network interface, making it useful for troubleshooting network issues, analyzing performance, and detecting security threats. By filtering the captured data, users can focus on specific protocols, IP addresses, or ports. This tool is widely used by network administrators and security professionals due to its ability to provide detailed insights into network activity. tcpdump operates on various operating systems, including Linux, macOS, and Windows, making it a versatile choice for network analysis.