PhotoPlus X6 User Guide - Serif

Making Image Adjustments 39
An adjustment layer is created by selecting an adjustment from the Adjustments
tab. As its name suggests, an adjustment layer is considered a layer so it will
appear in the Layers tab on creation.
Unlike the other layer types, adjustment layers don't store content in the form of
bitmap images, text, or shapes. Rather, an adjustment layer applies the
adjustment to content on all layers below it (although you can restrict the effects
of the adjustment by adding to a group or by clipping to the immediate layer
below).
The layer is essentially a container in which only the adjustment's settings and its
layer properties are stored.
You can drag an adjustment layer up or down within the list to determine
exactly which other layers are below and therefore affected by it.
Adjustment layers let you revisit the settings for a given adjustment as often as
needed, while continuing to edit the image in other ways. If you later decide you
don't even need an adjustment, you can simply remove it!