Understanding of computer network port number

POS machine debugging needs to set the port number, look down "computer Networks Road" This book, the following is my reading after the understanding, do not know the classmate can see help understand.

The difference between reuse and separation

Transport layer reuse means that the transport layer above the data are sent to the transport layer, transport layer sent out, divided by means that the other host sent over the data to be sent to the transport layer, and then transport in accordance with the port number sent to different processes, the function of the division.
Port definition: According to the book I understand is that in the computer network, seemingly is the communication between two computers, actually two computers in the communication between two processes, such as between the mailbox and the mailbox, my QQ and your QQ, Data through the IP protocol sent to the other side of the host need to send the relevant data to the corresponding process, so give each process a port number, such as my QQ port number PID is 4868, each transport layer received the destination port number data can be delivered to my QQ through this number, Then I can chat happily, this number can be recognized is the representation of the process, you can also think of the application layer and transport layer of a network interface.
The port number can be queried in the Task management tool, you can also enter Netstat-ano in the command number to view
Where the PID is the port ID port number

tasklist | Findstr "7616" This command can be viewed through the port number process

Understanding of computer network port number