Representational State Transfer (REST) is an architectural style that defines the architectural quality attributes of the World Wide Web, seen as an open, loosely coupled, massively distributed and decentralized hypermedia system. REST has seen a large uptake for the last several years, as it is largely regarded as a simpler and more Web-like way of exposing service interfaces, in particular when compared with earlier approaches such as the rather complex and heavyweight SOAP/WS-∗ and similar RPC-inspired protocols. As with all success stories, there also is the downside that pretty much any HTTP-based service is being promoted and sold as being "RESTful" these days, even though many do not completely follow the architectural principles and constraints underlying the REST style. However, in the end this may be the fate of every successful "brand name": once it becomes successful enough, it loses its purity and is used for marketing, where technical accuracy is not the main concern.
Pautasso, C., Wilde, E., & Alarcon, R. (2014, November 1). Introduction. REST: Advanced Research Topics and Practical Applications. Springer New York. https://doi.org/10.1007/978-1-4614-9299-3_1