Wireshark is a free and open-source network protocol analyzer that allows users to capture and examine data packets traveling over a network. It provides a graphical interface to visualize the data, making it easier to understand network traffic and troubleshoot issues. Users can filter and analyze packets in real-time or review saved capture files for detailed analysis. With Wireshark, network administrators and security professionals can identify problems, monitor network performance, and detect unauthorized access. It supports a wide range of protocols, enabling users to dissect and interpret the data at various levels, from the physical layer to the application layer.