The ability to build a hand which contains special combinations – or Yaku – is the essence of Mahjong. Yaku bestow privileges on the player who successfully collects them and yield him a higher score if he completes his hand.
Certain special cases are also considered to be Yaku (see the Yaku Table). In one case, a Yaku can even be “bought” (see Going Riichi)1.
Consider the following example hands:
1. A hand with no Yaku:
This hand can be completed with 1-Bamboo or 4-Bamboo. It consists of two runs, two three-of-a-kind sets and a head of Dragon tiles (chun
). It will probably be a low-scoring hand because it contains no Yaku2
2. A two-Yaku hand:
In this example, the player has collected four runs of three3
, which is a Yaku
. Also, there are no 1s and 9s, winds or dragons in the hand and the player is not waiting for a 1 or 9 tile to complete his hand. This is a Yaku
. Moreover, the hand can be completed with one of three tiles, the 2-Bamboo, 5-Bamboo or 8-Bamboo, which increases the probability of success.
The second hand is much better than the first. It will most likely yield more points than the first because the Yaku called Pinfu and Tanyao are worth one point each. The more Yaku a hand contains, the more points a player can win.
Furthermore, the value of the hand is augmented by the Red Five, which will earn a bonus point if the player goes out.