What are TCP segments and UDP datagrams?

TCP segments and UDP datagrams are indeed data chunks created by the Transport Layer of the OSI model. The Transport Layer is responsible for providing reliable (in the case of TCP) or fast and efficient (in the case of UDP) delivery of data between applications running on host devices.

TCP segments specifically come from the Transmission Control Protocol, which ensures that data is transmitted reliably, in the correct order, and without duplication. Each segment contains not only the application data but also important control information such as sequence numbers and acknowledgment information.

UDP datagrams, on the other hand, originate from the User Datagram Protocol. This protocol is characterized by its simplicity and efficiency, providing a connectionless communication method where data is sent without establishing a dedicated end-to-end connection. Each datagram contains the data payload along with headers that contain source and destination ports but offer little in terms of reliability.

Thus, TCP segments and UDP datagrams are essential building blocks of how data is transmitted over the network, directly tied to the functionalities provided by the Transport Layer, which includes error checking, flow control, and ensuring data integrity for TCP.