Waits are tiles a player does not possess in the hand, but they are wanted tiles either by draw or discard. Knowing the waits is essential to hand development. The process of identifying waits occurs throughout the game of mahjong: from the starting hand, interim, and to the state of tenpai. In particular, it is important to note these waits during tenpai, or even beforehand, to avoid furiten.
In addition, the type of wait used during tenpai for the winning tile(s) may factor into the amount of minipoints, or fu. Fu is relevant for any hand scoring 4 or less han.
Reading a hand[]
For every hand, a shanten number can be identified. This number is a tool to count the number of tiles needed in order to achieve tenpai. Given the initial deal and the draw-discard progress of a hand, players look for various yaku that their hands will potentially have. They sense and figure the likelihood of winning a hand, the hand's value, and the necessity to attack or defend.
Beginning players, mostly concentrate on completing their hands until they master more advanced yaku. They will often keep their hands closed so that they can get a late yaku by rīchi or menzen tsumo, the former allowing a player to win by ron while the latter by itself does not. More experienced players may be able to look at their tiles and have a general idea on the best tiles to keep and discard.
At any given time, a hand will usually have multiple tiles that will improve the hand. These tiles are called waits. Hands can be improved by:
- Moving one step closer to winning (reducing the shanten number)
- Increasing the potential value of the hand
- Increasing the chances of either case occuring.
Waits may refer to either the number of different kinds of tiles or the total number of instances of those tiles. In doing so, it is helpful to recognize the types of waits in the hand. It is not necessarily important to know the names of each wait type. Instead, it is better to focus on the patterns and identify the desired tiles.
Wait types[]
There are numerous types of waits and patterns. The following are the basic types, which can be combined.
Ryanmen[]
| 1 | 4 | 7 |
| 2 | 5 | 8 |
| 3 | 6 | 9 |
Ryanmen, or open waits, are two or more types of tiles being waited on. These apply to sequences, or shuntsu.
.
This pair is waiting on either a 
or 
to complete a meld.
For these waits, they follow the pattern on the "mahjong octaves" table, or suji. The suji follow the standard 1-4-7, 2-5-8, 3-6-9 patterns. If a player is waiting on a 4, then the additional wait could be a 1 and/or 7. If the player is waiting on a 1, then the additional wait could be a 4 and maybe even a 7. Likewise, this table is applicable to determining furiten.
Ryanmen may also combine to form more complex waits, which strings various wait patterns together.
Kanchan[]
A kanchan, or closed wait, applies to shuntsu, in which the middle number is the tile waited on.
This example pair needs a 
inbetween the 5 and 7 for completion. Often times, it is helpful to have a string of kanchan during hand development.
In this example, the three tiles compose of a pair of kanchan, in which they share the 
. Together, this group of tiles is waiting for either the or 
. A player may then complete a shuntsu of 5-6-7 or 7-8-9, and then the outside tile of 5 or 9 could be discarded, unless a complete string of tiles 5-6-7-8-9 is desired.
Penchan[]
A Penchan is an end wait, which is limited to waiting on a single 3 or 7 tile, where the tiles in possession are 1-2 or 8-9 respectively.
Shanpon[]
Shanpon, or dual pon, involves a double wait to complete one of existing dual pairs of tiles.
For example:
To complete this hand, only one more of either the 
or 
are needed.
Tanki[]
Tanki, or pair waits, are waits for a single tile to complete the pair. This applies to a hand in tenpai which the hand is already composed of four melds and the pair is left incomplete. Otherwise, similar waits for hands in noten often involve isolated tiles.
For example:
The example hand already has the 4 main melds completed, and there is a single waiting for another 8 to complete the pair.
However, the pair wait may actually not be limited to just a single tile. See Multiple pair waits.
Karaten[]
Karaten is essentally a "dead wait". All possible winning tiles are in the discards or are visibly inaccessible. Therefore, a tenpai hand in this state cannot win the hand by virtue of unavailable tiles.
Other wait patterns[]
The above are the basic wait patterns. More complex wait patterns may occur, and often, they involve a combination of the above waits, particularly involving the open wait (ryanmen). These involve waits on 3 or more tiles and may be explored separately.
See Complex waits.
Visible tiles[]
Visible tiles are naturally the tiles visible to the player. Tiles in the wall and in opponent hands are generally concealed, but during the course of the game, more and more tiles become revealed in the discard pile, open calls, and the dora indicator, where applicable.
Isolated tiles[]
Isolated tiles are single tiles in the hand. No other tiles in the hand does not pair up with the isolated tile, such that it cannot even wait to complete a meld.
In this hand, the tiles 
, 
, and are all isolated. Unlike 
, the isolated tiles do not have any "adjacent" tiles currently within the hand, and this hinders the ability to produce a meld within the next draw.
WWYD[]
WWYD, or What Would You Discard, is a puzzle, in which a player may examine the state of a hand after a drawn tile with or without a given scenario. As in the case of mahjong, a player must decide what to discard during his/her turn. WWYD is a screenshot of a mahjong hand during this state. As players, it becomes the objective to make the best decision regarding the impending discard. Part of this thought process involves selecting the best tile to discard, to maximize possible waits. WWYD helps players make thorough considerations on a discard, without the time pressure of an actual game.