The name Scrabble is a trademark of Mattel in most of the world, except in the United States and Canada, where it is a trademark of Hasbro. The game is sold in 121 countries and is available in 29 languages; approximately 150 million sets have been sold worldwide, and roughly one-third of American and half of British homes have a Scrabble set. There are approximately 4,000 Scrabble clubs around the world.
The game is played by two to four players on a square game board imprinted with a 15×15 grid of cells , each of which accommodates a single letter tile. In official club and tournament games, play is between two players or, occasionally, between two teams, each of which collaborates on a single rack.
The board is marked with "premium" squares, which multiply the number of points awarded: eight dark red "triple-word" squares, 17 pale red "double-word" squares, of which one, the center square (H8), is marked with a star or other symbol; 12 dark blue "triple-letter" squares, and 24 pale blue "double-letter" squares. In 2008, Hasbro changed the colors of the premium squares to orange for TW, red for DW, blue for DL, and green for TL, but the original premium square color scheme is still preferred for Scrabble boards used in tournaments.
In an English-language set, the game contains 100 tiles, 98 of which are marked with a letter and a point value ranging from 1 to 10. The number of points for each lettered tile is based on the letter's frequency in standard English; commonly used letters such as vowels are worth one point, while less common letters score higher, with Q and Z each worth 10 points. The game also has two blank tiles that are unmarked and carry no point value. The blank tiles can be used as substitutes for any letter; once laid on the board, however, the choice is fixed. Other language sets use different letter set distributions with different point values.