What is a characteristic of the RESTful system?

A RESTful system is characterized by its statelessness, which means that each request from a client to the server must contain all the information the server needs to fulfill that request. This design principle allows RESTful services to scale more effectively and improves the reliability of interactions between clients and servers. As there is no client context stored on the server, each interaction can be handled independently, reducing the overhead associated with maintaining session information.

In contrast, systems that rely on sessions to maintain context (like certain traditional web applications) create a dependency between requests, which can complicate scaling and increase resource usage. The aspect of real-time data processing is not strictly a characteristic of RESTful systems, as REST is more about resource representation and statelessness than real-time interaction. Lastly, while file transfers can occur in RESTful services, they are not a primary function; REST is more about accessing and manipulating resources over the web in a uniform manner. This makes stateless operation a defining characteristic of RESTful systems.