Sidespin (english)
The term english (called "side" in the UK, and sometimes simply called "left" or "right", and sometimes "check side" for side that narrows the cue ball angle after contacting a rail, and "running side" for side that widens the cue ball angle after contacting a rail) normally refers to sidespin put on a cue ball by hitting it to the left or right of center. Generally, english is used to change the angle of reflection of the cue ball after it contacts a rail. English also affects the direction an object ball takes on impact (the "throw" effect), as well as the path of travel of the cue ball after impact with a cue ("deflection" or "squirt").
Sometimes english is conflated to refer as well to spin imparted on the vertical axis of the cue ball. However, an above center hit is more precisely referred to as "follow" ("top" in the UK), and a below center hit as "draw" ("screw" or "back spin" in the UK). Any time the cue ball is not struck directly in the center, some spin will be imparted, whether left or right english, follow or draw. Unintentional sidespin is a common source of missed shots. Spin is not always placed on the cue ball by the shooter; spin is naturally imparted to the cue ball from contact with pool cloth on the bed of the table and on the table's cushions.
Read more about this topic: Cue Sports Techniques