What is REST?

Before getting into the details of REST, and since it is a style for communication between systems, let's first have a quick dive into the actual protocol that it uses, on which this whole book is based.

HTTP

The Hypertext Transfer Protocol (HTTP) is a request–response protocol that belongs to layer 7 (the application layer). This layer interacts with the application itself. Some other protocols that belong to layer 7 are the Simple Mail Transfer protocol (SMTP), Network File System (NFS), and the File Transfer Protocol (FTP), to name a few.

HTTP was designed to be used by clients (user agents) to request resources from a server. These resources can be HTML files or any other content, such as JSON...