Representational State Transfer is the name of the method used to communicate with the APIs. As the name suggests, it is stateless; in other words, the services do not keep the data transferred, so if you call a microservice sending data (for example, a username and a password), the microservice will not remember the data next time you call it. The state is kept by the client, so the client needs to send the state every time the microservice is called.
A good example of this is when a user is logged in and the user is able to call a specific method, so it is necessary to send the user credentials (username and password or token) every time.
The concept of a Rest API is not a service anymore; instead of that, it is like a resource container available to be communicated by identifiers (URIs).
In the following lines, we will define some interesting conventions about APIs. It is important to know these kinds of tips because you should do things as you would like to find them...