Flower Tiles
When Flower tiles are drawn or dealt, they must be replaced by a tile from the dead wall straight away. If not dead wall is available, then they should be replaced from the back of the wall.

Flower tiles may or may not have a value and indeed in some variations of Mahjong Rules, having all of the flower tiles wins the round regardless of the actual contents of the hand.

Melds
When a player discards a tile, any other player may make a call or a bid for that tile so that they can complete a meld. Unfortunately when doing this they must now expose the formed meld to the other players. This can give them an inkling as to what kind of hand they are building.

Most variants allow three different types of melds. When a meld is declared through a discard, the player must state the type of the meld and place the meld face-up.

Pongs or Pungs
A pong or its other name, pung, is a set of three identical tiles.

Kongs
To make a kong you need four identical tiles. Because all other possible melds contain three tiles a Kong must be immediately exposed when declared.

If the fourth tile to meld the hand is gained from a discard then it is said to be an exposed Kong. If the four tiles were formed within the hand then it is called a concealed kong. If you have an exposed pong then you can add the forth tile to produce a kong. A declared kong cannot be split, therefore, it may be advantageous not to immediately declare a Kong.

Chows
A chow is a meld of 3 tiles in sequence that are suited. Unlike other melds, an exposed Chow may only be declared off the discard of the player on the left.

Eye
A pair is not a meld and cannot be declared or formed with a discard. It is the final component to the standard hand. As suggested, and for obvious reasons, a pair is two tiles that are exactly the same.