What is API

Answer 1

Go to this website,
https://jsonplaceholder.typicode.com/posts
This is an API, you can fetch data from here and use it in your applications instead of making your own data.
You can create your own APIs using technologies such as NodeJS, Express, etc, and make requests to these APIs using Javascript.
Hopefully, u'll understand it

Answer 2

Please use google or any other search engine.
There are many explanations allready out there

Answer 3

an API is like a waiter which serves your requests made to the restaurant.

Answer 4

It's a short for: APplication Interface

Answer 5

Dragonxiv how can I integrate an external API on WordPress blog?