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 tile-tracking alternatives to paper and pencil. Users are required to manually input played tiles via the keyboard, and the input is then subtracted from a separate letter pool representing total tile distribution. The user then counts or otherwise calculates the status of the remaining tiles. Notes are made on a separate piece of paper as necessary. The user is still tracking and counting tiles manually, and the risk of receiving an inaccurate count through human error remains roughly equal to the non-technological option. The migration of Scrabble to mobile devices and the popularity of the digital exclusive Words with Friends