APIs are the most common way programs and devices interact in modern computing. An API is a set of rules that describe how one program can connect to and communicate with another. As the name suggests, the REST API communicates the status of each transaction on every request, giving you development, performance, and resource advantages over other methods. REST has been evolving for more than two decades and is a very common approach to service-based and distributed architectures.

A resource is a basic concept for a REST API. A resource is an object that has a type, related data, relationships with other resources, and a set of methods that act on it. It is very similar to the idea of ​​objects in programming, although only a few standard methods are defined, typical of HTTP GET, POST, PUT and DELETE. Resources can exist alone or in collections that are resources themselves.

In modern computing, the common model – also fundamental to API REST – is client-server, where a client who needs a resource identifies and communicates with a server that can provide it. Virtually all cloud traffic is managed in this way, as it offers maximum flexibility to multiple clients and allows access to multiple servers. This principle also applies to the so-called „serverless” architectures where the server known to the client is replaced by a service broker.