TCP is a synchronized communication session. It operates at session layer (4) of the OSI model. Standard applications typically adhere to standard destination service port such as http over port 80 or https over 443. TCP has specific flags that help communicate session state such as the 3 way hand-shake, and a FIN, Reset to name a few. UDP in comparison is session -less, meaning it does not look for an acknowledgment for every request. UDP is primarily used in streaming applications where low latency matters, like voice or video.