port
alias ： port number
Port is a sub address in the communication on the Internet, established below IP address to connect several machines at the same time. Computers that communicate with TCP/IP have an IP address, an address within a network, and several ports as a sub address to communicate with several computers at the same time. It is also called "port numbers" because numbers from 0 to 65535 are used to recognize it. Network address, which is the combination of IP address and ports is called "socket", the unit which is used to send and receive data. In the comparison with real addresses, the IP address is equal to the location of the apartment, and the port is the room number.