The character in a first- or third-person game will often need some collision-based physics so that it doesn’t fall through the floor or walk through walls. Usually, though, the character’s acceleration and movement will not be physically realistic, so it may be able to accelerate, brake and change direction almost instantly without being affected by momentum.
In 3D physics, this type of behaviour can be created using a Character ControllerA simple, capsule-shaped collider component with specialized features for behaving as a character in a game. Unlike true collider components, a Rigidbody is not needed and the momentum effects are not realistic. More info
See in Glossary. This component gives the character a simple, capsule-shaped colliderAn invisible shape that is used to handle physical collisions for an object. A collider doesn’t need to be exactly the same shape as the object’s mesh - a rough approximation is often more efficient and indistinguishable in gameplay. More info
See in Glossary that is always upright. The controller has its own special functions to set the object’s speed and direction but unlike true colliders, a rigidbodyA component that allows a GameObject to be affected by simulated gravity and other forces. More info
See in Glossary is not needed and the momentum effects are not realistic.
A character controller cannot walk through static colliders in a sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary, and so will follow floors and be obstructed by walls. It can push rigidbody objects aside while moving but will not be accelerated by incoming collisionsA collision occurs when the physics engine detects that the colliders of two GameObjects make contact or overlap, when at least one has a Rigidbody component and is in motion. More info
See in Glossary. This means that you can use the standard 3D colliders to create a scene around which the controller will walk but you are not limited by realistic physical behaviour on the character itself.
You can find out more about character controllers on the reference page.