Pinfu

Pinfu is a standard yaku. This yaku is defined by having 0-fu aside from the base 20. Though, this yaku may receive the bonus 10-fu acquired from a closed ron. This yaku is closed only.

Tile diagram

Winning tile: or

English reference

In English, pinfu is commonly referred as "all sequences". However, the yaku is not as simple as that. Other than having an open hand, it is possible for a hand to be composed of all sequences and still not be classed as a pinfu.

Fu

To understand pinfu, players must understand the nature of fu. Fu are a set of points associated with hand composition. Pinfu lacks any of these.