What are coaster brakes on a bike and how do they differ from other types of braking systems?

Coaster brakes are a type of braking system on a bike that are activated by pedaling backward. They differ from other types of braking systems, such as hand brakes, which are activated by squeezing levers on the handlebars. Coaster brakes are typically found on cruiser bikes and are known for their simplicity and ease of use.