I want to know what a basin is?

I found this in less than 10 seconds.

https://www.google.com/search?q=basin+geology&rlz=1C9BKJA_enUS699US700&oq=basin+geology&aqs=chrome..69i57j0l3.5840j0j8&hl=en-US&sourceid=chrome-mobile&ie=UTF-8