A RESTful API (Representational State Transfer API) is an application programming interface that conforms to the constraints of the REST architectural style. REST is a set of architectural constraints, not a protocol or a standard, that was created to guide the design and development of the architecture for the World Wide Web. RESTful APIs allow two computer systems to exchange information securely over the internet. They are based on representational state transfer (REST), which is an architectural style and approach to communications often used in web services development.
RESTful APIs use HTTP requests to access and use data, and the state of a resource at any given timestamp is called a resource representation. They support secure, reliable, and efficient software communication standards, making them ideal for most business applications that have to communicate with other internal and third-party applications to perform various tasks. RESTful APIs are scalable and easy to use, and they include benefits such as improved performance, flexibility, and portability.
API developers can implement REST in a variety of ways, and they explain how the client should use the REST API in the server application API documentation. HTTP-based RESTful APIs are defined with the following aspects:
- The resource identifier (URI) of one or several resources used as starting points, sometimes called endpoints or entry points.
- The encoding of all possible resource representations (which will include representation of the data and of the hypermedia links for state transitions).
- The possible state transitions and where they can occur.
RESTful APIs use HTTP methods defined by the RFC 2616 protocol, such as GET to retrieve a resource, PUT to change the state of or update a resource, POST to create that resource, and DELETE to remove it. Headers and parameters are also important in the HTTP methods of a RESTful API HTTP request, as they contain important identifier information as to the requests metadata, authorization, uniform resource.
