There are a range of adjustments which can be applied to your design as a new layer for corrective or creative purposes.
Adjustments are applied from the Adjustments panel and most include customisable settings alongside general adjustment options. Once applied, they can be identified as both an adjustment and a specific adjustment type by using unique symbols.
Adjustments can be symbolised, i.e. their settings can be updated across multiple instances of the adjustment layer at the same time.
When an item is selected, the adjustment layer is applied to just that item, i.e. it is clipped. With no selection in place, the adjustment is applied to the top of the layer stack.
Some adjustments (i.e., Curves, Levels, or Channel Mixer) can be made in any colour space independently of the document colour space.
The following are available from all adjustment general settings:
If there was no item selected, the adjustment is added to the top of the layer stack.