Strong / Weak / Neutral Grip
How far the hands are rotated on the handle, usually checked by how many knuckles of the left hand you can see at address.
A "strong" grip (more knuckles visible) tends to close the clubface and encourage a draw or hook; a "weak" grip (fewer knuckles visible) tends to leave the face open and encourage a fade or slice. "Neutral" sits in between.
See the full breakdown: Slice
Every common cause and fix for this exact issue.
See the full breakdown: Hook
Every common cause and fix for this exact issue.