Tile Caching
This area was greatly improved in Version 2.2 of GeoServer. From here you can control almost all parameters of the integrated GeoWebCache. It is a Java-based application that complements GeoServer. It caches WMS tiles to the filesystem. These images are then used by WMS clients instead of going to GeoServer for each tile request.
When creating a new layer, you may choose if it has to be cached or not. The Tile layers section lists all cached layers and lets you review and modify parameters. It also contains a link to a layer preview very similar to that listed in the data section. The main difference is that this preview uses cached tiles.
GeoWebCache is a companion for GeoServer, and if it is strictly integrated, there are a set of global parameters for configuring it too. Caching defaults is your entry point for them.
The Gridsets option lets you create new tiling schemas or modify the existing ones.
All the tiles you are going to create when caching need to be stored on a filesystem...