What makes an API "RESTful", and why does that suit network automation?

A RESTful API uses HTTP methods (GET, POST, PUT, PATCH, DELETE) on resources, and every resource or function has its own URL. Because HTTP is universal, the same tools and code work with APIs from different vendors.

REST stands for Representational State Transfer. In practice a RESTful API means:

• Resources have addresses. Each thing you can read or change, such as the device list or one interface, sits at its own URL, for example https://controller/api/v1/network-device.
• The HTTP method says what to do with that resource: read it, create it, replace it, change it or delete it.
• Data travels as JSON or XML in the request and response body.

The advantage for networks is uniformity. Every programming language and tool already speaks HTTP, so talking to a Cisco controller, a firewall or a cloud API looks the same: send an HTTP request to a URL, read structured data back.

Go deeper:

• REST — Wikipedia — the architectural constraints behind RESTful APIs.