The post-processing stack is an über effect that combines a complete set of effects into a single post-processing pipeline. This has a few advantages:
Effects are always configured in the correct order
It allows a combination of many effects into a single pass
All effects are grouped together in the UI for a better user experience
You can download the post-processing stack from the Asset Store.
For help on how to get started with the post-processing stack see Setting up the post-processing stack.
For details about each individual effect included in the stack see the page for that effect.