Overview of transport protocols.
The transport layer (OSI layer 4) is the interface between the network and application (network API).
The transport layer provides data transport service and some level of quality of service (QoS) to the application.
While all transport protocols offer data transport services, they have varying levels of quality of service in terms of error detection and correction, packet ordering and packet delay.
Simple transport protocols like UDP are often connectionless while connection-oriented transport protocols like TCP provide many quality of service properties.