Article: Although not specifically prepared to conduct independent strategic air operations against an opponent, the Luftwaffe was expected to do so over Britain. From July until September 1940 the Luftwaffe attacked RAF Fighter Command to gain air superiority as a prelude to invasion. This involved the bombing of English Channel convoys, ports, and RAF airfields and supporting industries. Destroying RAF Fighter Command would allow the Germans to gain control of the skies over the invasion area. It was supposed that Bomber Command, RAF Coastal Command and the Royal Navy could not operate under conditions of German air superiority.

Now answer this question: Why did the Luftwaffe bomb the RAF Fighter Command?
to gain air superiority