The US renaming of 'noughts and crosses' to 'tic-tac-toe' occurred in the 20th century. 'Tic-tac-toe' may also derive from 'tick-tack', the name of an old version of backgammon first described in 1558. The first print reference to a game called 'tick-tack-toe' occurred in 1884, but referred to 'a children's game played on a slate, consisting of trying with the eyes shut to bring the pencil down on one of the numbers of a set, the number hit being scored'.

The first print reference to 'noughts and crosses' ( nought being an alternative word for 'zero'), the British name, appeared in 1858, in an issue of Notes and Queries. The different names of the game are more recent. Another closely related ancient game is three men's morris which is also played on a simple grid and requires three pieces in a row to finish, and Picaria, a game of the Puebloans. The game's grid markings have been found chalked all over Rome. It was called terni lapilli ( three pebbles at a time) and instead of having any number of pieces, each player had only three thus, they had to move them around to empty spaces to keep playing. Īn early variation of tic-tac-toe was played in the Roman Empire, around the first century BC. Games played on three-in-a-row boards can be traced back to ancient Egypt, where such game boards have been found on roofing tiles dating from around 1300 BC. Tic-tac-toe's incidence structure consists of nine points, three horizontal lines, three vertical lines, and two diagonal lines, with each line consisting of at least three points. It can be generalised even further by playing on an arbitrary incidence structure, where rows are lines and cells are points. It can also be generalized as an n d game, specifically one in which n equals 3 and d equals 2. Harary's generalized tic-tac-toe is an even broader generalization of tic-tac-toe. The game can be generalized to an m, n, k-game, in which two players alternate placing stones of their own color on an m-by- n board with the goal of getting k of their own color in a row. If played optimally by both players, the game always ends in a draw, making tic-tac-toe a futile game. It is straightforward to write a computer program to play tic-tac-toe perfectly or to enumerate the 765 essentially different positions (the state space complexity) or the 26,830 possible games up to rotations and reflections (the game tree complexity) on this space. Hence, tic-tac-toe is often played by young children who may not have discovered the optimal strategy.īecause of the simplicity of tic-tac-toe, it is often used as a pedagogical tool for teaching the concepts of good sportsmanship and the branch of artificial intelligence that deals with the searching of game trees. Players soon discover that the best play from both parties leads to a draw. There is no universally agreed rule as to who plays first, but in this article the convention that X plays first is used. In the following example, the first player ( X) wins the game in seven steps: Tic-tac-toe is played on a three-by-three grid by two players, who alternately place the marks X and O in one of the nine spaces in the grid. Sometimes, tic-tac-toe (where players keep adding 'pieces') and three men's morris (where pieces start to move after a certain number have been placed) are confused with each other. While the term 'nought” is now less commonly used, the name 'noughts and crosses' is still preferred over the American name 'tic-tac-toe' in these countries. This name derives from the shape of the marks in the game (i.e the X and O) 'nought' is an older name for the number zero, while 'cross' refers to the X shape. In Commonwealth English (particularly British, South African, Indian, Australian, and New Zealand English), the game is known as 'noughts and crosses', alternatively spelled 'naughts and crosses'. It may also be spelled 'tick-tack-toe', 'tick-tat-toe', or 'tit-tat-toe'. In American English, the game is known as 'tic-tac-toe'. It is a solved game, with a forced draw assuming best play from both players. The player who succeeds in placing three of their marks in a horizontal, vertical, or diagonal row is the winner. Tic-tac-toe ( American English), noughts and crosses ( Commonwealth English), or Xs and Os ( Canadian or Irish English) is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid with X or O.

Tic tac toe grid to type in