push flag (PSH)
The push flag is a bit indicator of the control flag field in the TCP header, which takes over the internal control of the data packets.
The flag is always transmitted during the connection setup. If the flag is set, the data must be processed further using the Data Stream Push Service, i.e. the TCP protocol must forward the data to a higher layer. If the flag is not set, the data can be placed in the send or receive queue.