What is a birds eye view
A bird's eye view is a type of camera shot taken from an elevated position. Kind of like what a flying bird would see. The angle of this type of shot varies a lot, from a 90-degree overhead shot to a 40-degree angle. It can have many flavors, but the constant is the elevation from the ground.
Bird's eye view has many names that are used interchangeably. Overhead shot, top shot. Aerial shots and god's eye view are further away. All follow the same elevation rule, but the angles and distance may differ.
How to shoot a bird's eye view
To perform this, you need equipment, and the type you need depends on the shot's location. For an overhead shot that's straight above looking down. You can use an overhead rig if the shot is close and you are short of space. For bigger and more grand shooting, a crane shot or a jib arm is optimal. A drone and a ladder are viable options as well.
Why use a bird's-eye view
There are many benefits of using a bird's eye view. It's good to keep in mind that it has to fit the storyline, not cutting it in at random to risk confusing the audience. This shot is advantageous to get an overview of the setting. Use it as an establishing shot, illustrate the crowd and magnitude of a location.
There are many emotional components accomplished with this view. Portray dominance, camera looking down from a position of power. It can also highlight solitude, the thrill of a movement like a car chase, a spiritual plead.
A powerful example of a spiritual plead in one of the best films of all time. In this epic scene in Shawshank Redemption, Andy Dufresne gets out of the sewer tunnel. He raises his hands, laughing like he's pleading to god. The camera looking down while the rain pours, a classic birds-eye view.