Why Does the SpaceX Starship Do a Belly Flop?

If you've seen the launches and attempted landings of the SpaceX Starship prototype, you may be wondering why it does a belly flop and last-minute flip to vertical just before landing. 

Here's a video, from the excellent Everyday Astronaut YouTube Channel that explains why. It does get moderately technical, but it's likely as clear an explanation of the reason for the manoeuvre as you will find anywhere. 

If videos aren't your thing, there is an article version that you can read at your leisure.