Kitesurf bindings come in many different styles and configurations but they have one purpose, to hold the riders feet securely to the board while riding. They are especially useful in rough water when even riding can be difficult and during jumps and airs where the rider cannot hold onto their board. The differences in style allow a rider to choose which bindings will be best suited for their needs.
The most popular kitesurf bindings are very similar to wind surfing bindings. They have a durable strap that goes across the instep of the foot and often another strap in the back to prevent the foot from slipping out. The straps are very adjustable making these bindings suitable for many riders. One common variation is a backless binding which forgoes the rear strap so the rider can get their feet into the binding easier and take it out, often in the air to make a trick look that much more stylish.
Another type of kitesurf bindings are fully enclosed wakeboard style bindings which give the rider a full boot that has to be slid onto the foot. They have much more support and are unlikely to eject the foot even during a hard landing. Many advanced riders use these bindings because of the level of support offered which is especially useful when landing huge airs. These are the most expensive bindings as well.