Roy Thomas Fielding is the main person behind the formalization of the HTTP protocol and the REST style: he described them in his dissertation, Architectural Styles and the Design of Network-based Software Architectures (https://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm). Moreover, Fielding's dissertation clearly defines the constraints of a REST system, as follows:

• Uniform interface
• Stateless
• Cacheable
• Client-server
• Layered system
• Code on demand

All of these, apart from code on demand, are essential when we wish to define a web service as REST-compliant. To explain these concepts, we will use the APIs provided by The New York Times: https://developer.nytimes.com/. To use these APIs, you need to go through a pre-authentication process. You can get an API key for this from the following link: https://developer.nytimes.com/signup.