TCP and UDP Ports.

Reference : http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers

The port numbers are divided into three ranges:
* The Well Known Ports are those in the range 0–1023. On Unix-like operating systems, opening a port in this range to receive incoming connections requires administrative privileges or possessing CAP_NET_BIND_SERVICE capability.

* The Registered Ports are those in the range 1024–49151.

* The Dynamic and/or Private Ports are those in the range 49152–65535. Randomly chosen port numbers out of this range are called ephemeral ports. These ports are not permanently assigned to any publicly defined application.