Connecting to a Grid is one line. Owning one is infrastructure work, and at senior level in a Selenium organisation it is often your responsibility.
The components, in the modern architecture. Grid 4 splits what used to be a hub into named parts, and knowing them matters when you are diagnosing a stuck queue:
Router receives all requests and forwards them. Distributor decides which node runs a session and creates it. Session Map remembers which node holds which session. Session Queue holds requests waiting for a free slot. Node runs browsers.