Checkering
A pattern of fine cut or pressed diamonds in a grip surface that adds texture for a more secure hold. Found on stock grips and forends.
Checkering is a grid of shallow lines cut or pressed into a gripping surface so it forms a field of tiny diamond points. Those points give the hand something to bite into, keeping the hold secure when conditions are wet or the rifle is worked hard. It is the traditional treatment on the wrist and forend of a rifle stock.
On precision rifles, molded stippling and aggressive synthetic textures have largely taken over the same job, but the purpose is unchanged: a positive, repeatable hand position. Consistent hand placement matters most in unsupported offhand shooting, where grip is doing real work to steady the rifle.