A turn
On your turn you draw the next tile from the , then one, face up, naming it. There is one exception: .
means claiming a tile someone else just discarded. Any of the other three players may do it, out of turn, until the next player has drawn a tile and racked it (put it in her hand) or discarded. The caller takes that tile instead of drawing, and play continues from the caller. For example: you hold two 7 Dots, the player across a 7 Dot, you say 'call', take it, and lay the three 7 Dots on top of your .
You may only take a if it completes a , or from your hand. When you do, that whole group goes on top of your , , for the rest of the game. may sit in an exposed group. A discarded Joker can never be called.
You cannot take a just to make a , except for the last tile that wins you the game.
Once you expose a group, you are committed to hands that use it. That is why players think before .
When can you take a discard to complete a pair?