Go Fish or Fish is a card game for approximately two to five players, often played by children. Five cards are dealt from a standard 52-card deck to each player, or seven cards if there are only two or three players. The remaining cards are placed face down, usually spread out in a disorderly pile. The player whose turn it is to play asks any other player for their cards of a particular rank. When any player at any time has four cards of one rank, they form a book, and the cards must be placed face up in front of that player. The winner is the first player to run out of cards in their hand by laying them down in books of four cards.

Source: Wikipedia