Skating is a
phenomenon in a record player where the
stylus (and its attached
cartridge and
tonearm) is forced towards the center of the record by the inward momentum imparted by the
LP's center-spiraling groove on the pivoting tonearm.
Linear-tracking turntables, in which a non-pivoting tonearm rides a rail on a
perpendicular path to the grooves in the vinyl record to ensure right-angle stylus contact, do not exhibit this phenomenon.
Every pivoting-arm turntable has an Anti-Skate mechanism to counteract this, usually by providing a counter-force matched to the tracking pressure of the stylus on the record. The higher the tracking force, the more anti-skate correction needed. This mechanism can range from a weight on a string (often used in high-end turntables to minimize device coupling) to spring tension controlled by a dial at the tonearm pivot point.
If anti-skate correction is not performed, the stylus will press harder against the outer side of the groove, and if overset, will cause the stylus to press more against the inner side of the groove. Obviously the goal is to get the balance just right so that the pressure is equal; this creates the best stereo separation, tracking, and performance in general.