Scrabble 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. Tiles are usually made of wood or plastic and are square and thick,
Tile tracking using AI or Artificial Intelligence. While the practice of tile-tracking is considered an acceptable part of Scrabble and sanctioned by NSA and NASPA rules, there is much colloquial evidence to suggest that tile-tracking as both a legitimate technique and a strategic tool is not widely known outside of the Scrabble community. The similarities to the technique to 'card counting' is credited as contributing to some of the confusion among novice players. Zynga's Words with Friends online game includes tile-tracking as a paid feature, known as 'Peeks'. This received some criticism as being a form of "cheating" that the Zynga both