A pocket is a hole or recess in a climbing hold that fits only one, two, or three fingers, requiring precise placement and finger strength. Pockets are common on limestone and on moulded gym holds, and the number of usable fingers — a one-finger pocket is a 'mono' — defines how hard it is and how much it stresses the tendons.
A jug, also called a bucket, is a large, easy-to-grip climbing hold with a deep, positive edge you can wrap your whole hand around. Jugs are the most secure and beginner-friendly holds, often marking rests or the start of a route, and let climbers hang comfortably even when tired.
A dihedral is an inside corner where two rock faces meet at an angle, like the open pages of a book — also called a corner or open book. Climbers ascend dihedrals using opposing pressure between the two walls, with techniques such as stemming, laybacking, and jamming any crack in the corner.
An arete is a narrow, outward-facing edge or ridge of rock where two faces meet, often formed by glacial erosion. In climbing, aretes offer distinctive, frequently photogenic lines that require balance and techniques like laybacking and flagging to climb the edge itself rather than a face or crack.