NetFlow is a network protocol developed by Cisco that collects and analyzes network traffic data. It provides insights into the flow of data packets across a network, helping administrators understand bandwidth usage, identify performance issues, and detect potential security threats. By capturing information such as source and destination IP addresses, port numbers, and the amount of data transferred, NetFlow enables organizations to monitor their network's health. This data can be used for capacity planning, troubleshooting, and optimizing network performance, making it a valuable tool for network management.