Is the concept of sessions part of the REST architectural style?

The concept of sessions is not part of the REST architectural style. REST (Representational State Transfer) assumes that the server does not store the client's state between requests — that is, REST is stateless.

This means that each request from the client to the server must contain all the information necessary for its processing, without relying on previous requests.

Using sessions that store state on the server (for example, a session ID associated with a user) violates the stateless principle and does not conform to pure REST.

If state needs to be preserved, it is usually done on the client side (for example, using tokens), which are transmitted with each request.