Definition
A discard is the tile a player places face up in the centre after drawing, named aloud so that any player may call it.
Naming the tile is part of the rule, not a courtesy: a tile discarded silently, or named wrongly, can be challenged. Discards stay face up and are the table's shared memory of what has already gone.
Read the full guide: Calling and Exposing in American Mahjong: When, How, and When Not To.
See it on real tiles: the coach reads any hand and names its direction, free, at the free read. Members get the coach on call for their own games.
More terms: Pung, Kong, Quint, Pair, Charleston, Blind pass, Courtesy pass, Joker.