The glue between the frontend and backend
An Application Program Interface (API) is a set of defined functions that access data, perform operations, and decouple applications.
Representational State Transfer (REST) is a software architecture for developing web services.
Bringing these two concepts together, a REST API is a web service that has defined functions to retrieve data and perform operations. They decouple applications and works as a middle man between the frontend and the backend.
A Beginner’s Tutorial for Understanding RESTful API
They can be developed in most of the popular programming languages and are usually paired with a web framework. Some examples of this are Java and Spring, Javascript and Node/Express, and Python and Flask.
REST APIs live on the backend. This means they generally run on a remote server.
Generally, REST APIs use the HTTP protocol to communicate with the outside world. Each action will be assigned a URL path and accessed by a GET/POST/PUT/DELETE method. A great tool for working with APIs is Postman.