It's the most simple, unassuming, innocent-looking verb: 'to be'. Yet it is jam-packed with more different meanings, forms and uses than any other English word. As he reveals ‘be's’ multiple incarnations, Prof Crystal takes us to the heart of our flexible and changing language. We meet circumstantial be ("how are you?"), numerical be ("two and two is four"), quotative be ("so I was like, 'wow'"), and ludic be ("oh no he isn't!"), and a whole swarm of other meanings.