What REST APIs Are and Why Every Web Developer Should Understand Them

REST (Representational State Transfer) APIs are interfaces that allow applications to communicate over HTTP, forming the backbone of most modern web and mobile development. They enable a single backend to serve multiple clients simultaneously — such as a website, mobile app, and admin dashboard — without duplicating infrastructure. REST APIs use standard HTTP methods (GET, POST, PUT, PATCH, DELETE) to perform create, read, update, and delete operations on resources, with JSON as the most common data format. Security in REST APIs relies on two distinct concepts: authentication, which verifies a user's identity typically via tokens like JWT, and authorization, which governs what actions that user is permitted to perform. Developers are also advised to always validate user input on the backend, since frontend validation alone can be bypassed.