An API endpoint is a unique URL that receives requests and sends responses between various applications. This is necessary as it provides an interface that allows the communication and data transfer between different parties.

An analogy for API endpoints is a waiter at a restaurant. The waiter is the endpoint, with requests being made to the waiter from the customer and responses being sent back from the waiter to the customer. The waiter stands in the middle, processing and delivering orders from the kitchen to the customer. In the same way, API endpoints stand in the middle, processing and delivering requests to their designated receiver.