

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. 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. 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, Australian and New Zealand English), the game is known as "noughts and crosses". 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.
