There are a few different ways to stop a train on a roller coaster. This is a very important step, as braking keeps the train from going over hills with too much speed, and it keeps the train from crashing into other trains at the station. Missing brakes can cause serious injuries, and it is important that they always work. As brakes work, they use an increase in friction to stop the train. When this happens, there is an increase in heat as the moving parts slide past stationary parts. It is important that all brakes are properly cooled so they do not malfunction. There are two kinds of brakes. Below is a comparison of the two.
Trim Brakes: These are used to slow the train down in potentially dangerous situations where the speed could be too high for the track or passengers to handle. These cannot stop the train.
Block Brakes: These are used for stopping the train. They can also slow it down without completely stopping it, but their main function is to stop the train.                               

There are also three types of brakes. Below is a comparison of these brakes.
Skid Brakes: These are long pieces of material that push up on the bottom of the train, producing friction that stops the train. They are usually covered in ceramic to reduce the effect of added heat on them. However, these are not used in many new coasters.
Fin Brakes: These are extensions of the train that hang down over the rails of the track, and they have a squeezing mechanism on them. When squeezed, the fins create the friction that is used to stop the train. It has a fail-safe in case of power outage, and it is the most widely used brake today.
Magnetic Brakes: These consist of two rows of large magnets that, when a magnetic fin behind the train passes through, create a magnetic field that pushes in the opposite direction of the motion, causing the train to stop. These can be used in addition to other brakes, and they are very common among new coasters.

Skid brake. Image from:              
Fin brake. Image from:           
Magnetic brake. Image from: