Clipping mask
A layer whose visibility is confined to the opaque pixels of the layer directly below it — a common, non-destructive way to constrain artwork to a shape.
Also called: clipping group
A clipping mask “clips” one layer to the shape of another: the lower layer acts as a stencil, and the upper layer shows only where the lower layer has pixels. In mockups it keeps a pattern, label or texture inside a defined area — a bottle label, a screen, a fabric panel — without permanently erasing anything.
It differs from a layer mask, which uses a greyscale mask painted on a single layer; a clipping mask borrows the shape of the neighbouring layer instead.