For future use. Each bit of the control field functions independently. They define the use of a segment or serve as a validity check for other fields. If the URG control bit is set, the sender is informing the receiver that there are urgent data in the data portion of the segment. IP Datagrams and Datagram Forwarding TCP is a connection-oriented protocol and IP is a connectionless technology.
Information is transferred as a series of datagrams.
A datagram is a collection of data that is sent as a single message. This is a virtual packet that can be transferred across the underlying hardware intact. Each host or router in an internet contains protocol software that understands the internet packets. The size of the datagram is determined by the application that sends the data. Each router along the path receives the datagram, extracts the destination address from the header, and uses the destination address to determine a next hop to which the datagram should be sent.