What does 'middleware' refer to in web applications?

Middleware is a crucial component in web applications that facilitates communication and data management between different services, applications, or components. It serves as an intermediary layer that allows disparate systems to interact with one another, thereby enabling data exchange and functionality integration.

In a typical web architecture, middleware can handle various tasks, such as managing requests and responses, performing authentication, or processing data before it reaches the client or server. By acting as a bridge, middleware helps to streamline interactions between the front-end user interface and the back-end server processes, allowing for a more cohesive application structure.

The other choices focus on aspects of software that do not encapsulate the concept of middleware. For instance, one option refers exclusively to client-side applications, which do not describe the role of middleware as a connector between systems. Another option talks about programs that run only on the server, limiting the definition to a specific environment rather than to the broader function of enabling communication. Lastly, system software requiring minimal user interaction does not suitably address the communication facilitation aspect that middleware embodies. Thus, the definition that describes middleware as a layer of software connecting applications for communication accurately captures its role in web applications.