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,
Scrabble letter distributions not allowed. Official rules treat the "Q" tile as just one letter, but usually Catalan players use the "Q" tile like the "QU" digraph and all Catalan Scrabble Clubs use this "de facto" rule. "K", "W", and "Y" are absent because they are only used in loanwords or, in the case of "Y", the digraph "NY". Blanks cannot be used to represent "K", "W", or "Y". There is a Catalan Scrabble clone which uses the same 21x21 board as Super Scrabble. Croatian-language Scrabble sets use the following 103 tiles: "Q", "W", "X" and "Y" are not included, as Croatian does