Leg-spin (or leg break bowling) is, arguably, the most difficult style of bowling in cricket. Like all forms of spin, it is a difficult art to truly master. Unlike finger spin, it is more difficult to control because of the biomechanics involved.
The leg break is so-called because the ball spins from the leg-side to the off-side. This is taken from the position of a right-handed batsman. As such, a leg break spins away from a right-handed batsman, while it turns into a left-hander.
There are two basic characteristics of leg-break bowlers:
They are right-handed
They spin the ball with a wrist action
These two characteristics are very critical to defining a leg spinner. For instance, not all wrist spinners (spinners who generate spin from wrist action) are leg-spinners. A left-arm wrist spinner is known as aleft-arm unorthodox spinner. All other spinners rely on their fingers to generate spin, with the exception of the rather unique Sri Lankan off-spinner Muttiah Muralitharan. He relied on his fingers, wrists and even shoulders to produce prodigious turn.
Anyway, back to leg-spinners.
This type of bowler is an attacking option, whose stock delivery turns from leg to off to a right-handed batsman. Since wrist spin is harder to control, some loose deliveries are expected. Leg break bowlers rely on guile, turn, flight and bounce to outfox batsmen. In addition to these, the leggie has a number of variations. The best, like Shane Warne (708 test wickets), Stuart MacGill (208 Test wickets), Abdul Qadir (236 Test wickets) and Anil Kumble (619 Test wickets), have multiple variations in their arsenal.
This is the primary variation that any self-respecting leggie possesses. It is bowled with a leg-break action but turns from the off-stump to the leg-stump. For this reason, it is known as the “wrong ‘un” (wrong one). It is bowled by changing the wrist position of release.
A classic leg-spinner’s wrong ‘un would draw the batsman forward and have him playing for turn. However, the googly would zip through the gap between bat and pad, bowl the batsman or trap him leg before wicket.
Top-spinner/ Flipper/ Slider
These deliveries all continue on the original line after pitching, but they behave differently in terms of bounce and speed. The top-spinner describes a delivery that dips sharply on the batsman and bounces higher than other deliveries.
The flipper has more flight, but upon pitching it skids through to the batsman at a low trajectory. The slider is a faster ball that is pushed with minimal spin – Anil Kumble style.
Leg-spin was thought to be a dying art before Abdul Qadir and Shane Warne helped to restor it. Along with Warne, there are several other leggies who made a mark in the post-Qadir era. They are Anil Kumble, Mushtaq Ahmed and Danish Kaneria.
Even after Warne retired, promising leg-spinners continue to emerge, like India's Amit Mishra and West Indies' Devendra Bishoo. It is worth noting that two of the top three wicket-takers in Test cricket history (Warne and Kumble) are leg break bowlers.