Is Selenium a web Server?
Selenium isn’t a web server because it doesn’t have the features that we usually associate with one. Web servers do more than just open and close HTTP connections; they manage persistent connections to clients and route requests between those clients and back-end services (e.g., databases or other applications). As such, they are an integral part of any complex web application infrastructure.
A web browser is also not usually considered sufficient for running any sort of production service; in fact, the idea of using a browser for anything other than viewing content on the Web is absurd from the perspective of most IT professionals! The fact that Selenium is used for testing means that it’s not being used for its intended purpose (i.e., as a web browser).