UNO is a game played with a specially printed deck of 108 cards. The objective is to be the first player to score 500 points by discarding all your cards before your opponents do. Players take turns matching a card in their hand with the current card shown on the discard pile, either by number, color, or symbol. Special cards like Skip, Reverse, Draw Two, Wild, and Wild Draw Four add twists and strategy to the uno online game.