It is an inbuilt Network Monitoring Tool that examines TCP/IP activity on Windows computers. This feature gives you information on all TCP and UDP endpoints on your PC, including the remote address with domain names and the state of TCP connections

TCP Connections Click on the image for bigger view

When you start TCP Connections, it lists all active TCP and UDP endpoints. It also translates all IP addresses to the respective domain names. TCP Connections will display processes related to each endpoint in Windows NT, 2000 and XP. Apart from the auto updation per second, you can set timings of your convenience also. Dynamic endpoints, are highlighted in yellow.

To close established TCP/IP connections, you could choose Close Connections from the file menu or by right clicking on a particular connection and then choosing from the resulting menu.