Post-processing effects can be applied by adding components to the Camera or to a PostProcessVolume.
The built in effects: tonemapping and film grain.
Apply a set of effects only while the camera is inside a volume, with blending.
Write your own effect as a component plus a shader.
The Camera component has settings especially for post processing.
Disable to prevent post processing from rendering on this camera at all.
By default when triggering PostProcessVolume's we use the camera's position.
This isn't always the behaviour you want. For example, if you're making a top down game, you probably want it to use the player's position.
If this is set, we'll use the world position of that GameObject to find PostProcessVolume's instead of the Camera's position.