The transmission control protocol adjusts the work of the transmission of information where the parties agree on the size of the transmissions during the data transfer process (Window Size) as well as the use of the retransmission principle in the event of an error in the information received، This protocol also initializes the connection before data transfer (Connection-oriented). As for (user data protocol), unlike (transmission tuning facility), it does not use any means to adjust the data transfer process and the connection is not initialized before the transfer process (Connection-less). This layer specifies the mechanism of sending information, whether it is (Port Control Protocol) or (user data protocol), and also gives port numbers for each of the transmitted and received information.