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'''Yaku''' {{kana|役}} are [[List of yaku|specific hand patterns or conditions]] that score points, analogous to [[wikipedia:List of poker hands|poker hands]]. Each yaku is worth a specific amount of [[han]], and multiple yaku can be combined into one hand. Basic mahjong knowledge involves learning the yaku, but it is not expected of new players to know all of them.  '''Most importantly, every hand must include at least one yaku in order to count as a winning hand'''.

==Han==
{{main|Scoring}}

Each yaku is assigned a han value. Whenever a player wins, their hand's yaku are tallied up, and they score points based on the total amount of han. If a hand has multiple possible interpretations, the highest possible hand is scored.

===Open vs closed===
{{main|Menzenchin#Yaku}}
A hand is considered open if it makes a [[tile call]] from another player's discard. These include [[chii]], [[pon]], and open [[kan]]. Otherwise, it is closed.

Some yaku can only be scored closed; they are invalidated when the hand opens. Other yaku reduce in value if part of an open hand. The rest of the yaku score the same regardless if a hand is open or closed.

==Nomi==
'''Nomi''' {{kana|ノミ}} refers to a hand that contains only one yaku and no [[dora]]. For example, '''riichi nomi''' {{kana|リーチノミ}} means "riichi only". The term is mostly used for low value yaku, like [[tanyao]] and [[pinfu]]. It is acceptable to use it for higher value yaku, like [[chinitsu]], but this is rarely done. The term is not used for [[yakuman]], due to their value.

== Yaku types ==
[[Image:Yaku example 00.png|right|250px]]
[[Image:Yaku example 01.png|right|250px]]
[[Image:Yaku example 02.png|right|250px]]
[[Image:Yaku example 03.png|right|250px]]
[[Image:Yaku example 04.png|right|250px]]
[[Image:Yaku example 05.png|right|250px]]
[[Image:Yaku example 06.png|right|250px]]
[[Image:Yaku example 07.png|right|250px]]
The different yaku focus on different types of patterns and circumstances.  They are mostly derived from the tiles within one's hand.  A number of yaku also involve the state of one's hand pertaining to the timing of certain tile draws and discards.

===Riichi===
A player can choose to declare [[riichi]] with any closed hand that is [[tenpai]] (one tile away from winning).

* [[Riichi]]
: Any closed hand in tenpai may choose to declare riichi, scoring this yaku. 
* [[Double riichi]]
: A riichi on your first turn is a double riichi, which is worth more points.
* [[Ippatsu]]
: After declaring riichi, if you win by your next tile draw, you score this yaku. (Invalidated if anyone makes a [[tile call]].)

=== Win location based ===
These yaku are dependent on how you win the hand. These yaku can allow otherwise "yakuless" hands to win.

'''Discard based'''
* [[Chankan]]
:Winning with a tile used for an [[shouminkan|added kan]] by another player.
* [[Houtei raoyui]]
:Winning off of the last possible discarded tile for the hand.

'''Draw based'''
* [[Haitei raoyue]]
:Winning with the last tile draw.
* [[Menzenchin tsumohou]]
:Drawing the winning tile with a closed hand.
* [[Rinshan kaihou]]
:Drawing a winning tile after a kan call.

=== Honor based ===
These yaku depend on the use of [[honor]] tile groups. These may be mixed with number tiles.

* [[Honitsu]]
: All tiles are the same suit or honor tiles.
* [[Honroutou]]
: All tiles are honor or terminal tiles.
* [[Shousangen]]
: Two [[dragon]] triplets, and a pair of the third dragon.
* [[Tanyao]]
:No honors or terminals are used.
* [[Yakuhai]]
:A triplet of: your [[Jikaze|seat wind]], the round wind, or any dragon.

=== Sequential ===
These yaku require [[shuntsu|sequential]] tile groups.

* [[Iipeikou]]
: Two identical sequences (two sequences with same suit and numbers).
* [[Ittsu]]
: A complete string of 1-9 tiles, arranged into sequences of: 123, 456, and 789.
* [[Pinfu]]
: Every tile group must be a sequence (among other conditions).
* [[Ryanpeikou]]
: "Two iipeikou"; two sets of identical sequences.
* [[Sanshoku]]
: Three identically numbered sequences, one of each suit.

=== Terminal based ===
These yaku revolve around [[terminal]], or complete lack thereof.

* [[Chanta]]
:Every tile group, including the pair, has an honor or terminal.
* [[Honroutou]]
:Every tile is an honor or terminal.
* [[Junchan]]
:Every tile group, including the pair, has an honor or terminal.
* [[Nagashi mangan]]
:Every discarded tile is either a [[terminal]] or [[honor]]
* [[Tanyao]]
:No terminals or honors are used.

=== Triplet based ===
These yaku require at least one [[Koutsu|triplet]] in order to be valid. [[Kan|Quads]] count as triplets for these yaku, but triplets don't count as quads.
* [[Sanankou]]
: Three closed triplets.
* [[Sankantsu]]
: Three [[kan|quads]].
* [[Sanshoku doukou]]
: Three identically numbered triplets across the three suits.
* [[Shousangen]]
: Two [[dragon]] triplets, and a pair of the third dragon.
* [[Toitoi]]
: Every tile group is a triplet.
* [[Yakuhai]]
:A triplet of: your [[Jikaze|seat wind]], the round wind, or any dragon.

=== Suit based ===

* [[Honitsu]]
: All tiles are the same suit or honor tiles.
* [[Chinitsu]]
: All tiles are the same suit.

=== Yakuman ===
{{main|Yakuman}}
Yakuman is a special class of yaku, by which the pattern itself is awarded the maximum point limit for a single hand pattern.  These are among the most difficult to complete; and players may treat them as special.

== Combining yaku ==
{{main|Yaku compatibility}}
Different yaku may be implemented into a single hand.  By doing so, the values applied to the different yaku also combine.  In short, they stack.  This aspect of the game is key towards developing larger scoring hands.  With [[dora]], the stacking effect becomes even greater.

== Optional yaku ==
{{main|Optional yaku}}

A list of '''optional yaku''' exist due to the game's complexity, which can further explore possible tile combinations and patterns.  Regardless, the yaku list noted above is the more commonly accepted list.

== See Also ==

* [[List of yaku]]

==External links==
{{jpwiki|役_(麻雀)}}
* [https://en.wikipedia.org/wiki/Japanese_Mahjong_yaku Japanese mahjong yaku]
: Wikipedia listing
* [http://tenhou.net/sc/prof.html Yaku frequency among Tenhou.net players] ''(Japanese)''
:Lists all the yaku occurrences in [[Tenhou.net]] by percentages and by room
* [http://www.osamuko.com/top-10-hands-you-should-re-memorize-if-you-ever-lose-your-memory/ Yaku short list]
: Pointing out which yaku to learn first

[[Category:Terminology]]
[[Category:Yaku]]
[[Category:Scoring]]
{{Navbox yaku}}
{{Navbox yaku replays}}