Transport Layer

Why
The transport layer is important because it allows processes on hosts to view each other as logically connected

What
The transport layer is a protocol layer in a protocol stack that transports application layer messages between application endpoints.

Transport layer protocols can be distributed across multiple end users and they can send messages between them. A packet of data that's being transported is refered to as a segment

Examples of Transport Layer Protocols

 * TCP
 * UDP

How
A Household Analogy

Consider the scenario in which there are two families on two sides of the United States. Every month, they each write to each other. Also, assume that one kid on each family is responsible for collecting the mail and giving it to the post man. Then, we have the following analogy in place
 * Application Messages = letters in envelopes
 * Processes = cousins
 * hosts (also called end systems) = houses
 * transport-layer protocol = Ann and Bill
 * network-layer protocol = postal service (including mail carriers)