On International Scrabble Day, April 13, here’s everything you need to know about the world’s most popular word game.

A is for Alfred Butts. Unemployed New York architect Butts invented Scrabble in the 1930s having set out to create a game that combined skill and chance with the fad for anagrams and crossword puzzles.

B is for Board. The first Scrabble sets had only letters, and no board. Only when Butts gave up trying to find a distributor and sold the rights to entrepreneur James Brunot did the new owner create a board, add the bonus squares and trademark the game.

C is for Commercial. In 1948 Brunot came up with the name ‘Scrabble’, meaning ‘to grope frantically’, and, in a converted school house on Connecticut, he and his wife produced the first 2,400 sets, but lost $450 in the process due to poor sales. But word of the word game got round and a big order from Macy’s department store secured Scrabble’s future. By 1952 Brunot had to license a nationwide game maker to market and distribute the game. Some 150 million sets have been sold worldwide since, and 53% of UK homes are said to own a Scrabble set.

D is for Dictionary. The high point of any game of Scrabble was when Dad consulted the dictionary to check that the 75-point word you’d just put down actually existed. Any dictionary is accepted to adjudicate in social play, but for tournament play official Scrabble word lists must be used. These vary either side of the Atlantic, but for international competition a combined word list is used, containing a massive 267,751 words.

E is for Editions. Scrabble is available in 41 different languages including Esperanto, Latin and Basque. Each one has its own tile distribution and points system. In Polish, for instance, Z is worth just one point, while the Malaysian version has 19 ‘A’ tiles - almost a fifth of the 100-tile set.

F is for Facebook. The social media site has revived the fortunes of Scrabble by giving members access to various online incarnations. Lookalike app Scrabulous was picking up half a million players a day before joint Scrabble copyright holders Mattel and Hasbro made Facebook take it down in 2008. 18 months later Words With Friends - another clone made lawyer-friendly by the changing of some bonus squares and tile values - appeared on Facebook and soon proved more popular than the clunky official Scrabble app. It has now gone full circle - Words With Friends is now available as a physical board game.

G is for Gyles Brandreth. The author, ex-MP and Countdown regular founded the British Scrabble Championships in 1971, after recognising the universal appeal of a game which he had seen played by Bristol Prison inmates as well as by members of the Royal Family. Brandreth placed an ad for competitors in The Times, hundreds applied and 43 years on the tournament - which carries prize money of £2,500 - is still going strong.

H is for Harold! In one episode of sitcom Steptoe & Son, the rag and bone men are seen playing Scrabble. A half-second cut away to the board - which bypassed the censors in the days before video freeze-frame - reveals a large number of swear words, all played by ‘Dirty Old Man’ Albert, much to son Harold’s disgust. Their game would actually be invalid, not because of the rude words, but because the pair had broken the first rule of Scrabble - the first word must always be laid over the centre square.

I is for International. There are Scrabble World Championships in English, French and Spanish. The 13th edition of the English version was the fourth to be held in London and only the second to be won by a British player, Craig Beevers from Guisborough near Middlesbrough. The only other British winner was 1993 winner Mark Nyman. Nyman was Countdown champion aged 16 and later spent 12 years as producer on the words-and-numbers show.

J is for John. Mattel caused Scrabblers to choke on their tiles when it announced in 2010 that proper nouns - names, places and companies - would be allowed in its next edition of the game. There was no need to panic - while the news made for great headlines the rule change only applied to Scrabble Trickster, a version of the game which added Monopoly-style Chance cards. Nevertheless, some 350 proper nouns are acceptable as they have other meanings, including carol (the Christmas tune), gilbert (a unit of force), ruth (compassion - think ruthless) and, yes, john (slang for a toilet).

K is for Khoshnaw. Dr Karl Khoshnaw from Manchester holds the record for the highest word score achieved in a competition, scoring 392 points with CAZIQUES, the plural for a West Indian Chief.

L is for Lexico, the original name of Scrabble. Alfred Butts also sold the game as ‘Criss Cross Words’ and simply ‘It’ until James Brunot settled on ‘Scrabble’.

M is for Muzjiks. The highest number of points that can be scored on the first go is 128 - with MUZJIKS, a term for Russian peasants.

Scrabble

N is for Notation. As with chess, tournament Scrabble players use shorthand to record each move and score. Also like chess, the world’s top players are known as Grandmasters.

O is for Odds. In English-speaking Scrabble there is a one in eight chance that the first seven tiles you draw will make a seven-letter word. The tricky bit? Remembering all 32,909 seven-letter words in the official word list.

P is for Punctuation. In 2008, Hasbro tinkered with the idea of adding apostrophes and hyphens to the game to permit contractions such WON’T, DOESN’T and SHOULD’VE, as well as possessives such as HOUSE’S. The idea was eventually rejected.

Q is for Qi. QI is the most commonly played word in Tournament Scrabble. It’s pronounced ‘chee’ and means ‘life force’ or ‘energy’ in Mandarin.

R is for Rude words. Contrary to popular belief, profanities are allowed in Scrabble, as long as they are in the dictionary chosen for adjudication. The US Official Scrabble Players’ Dictionary - intended for school and home use - has no obscenities but the North American tournament word list does.

S is for Simpsons. In one episode of the animated show, Bart picks up a huge score for playing the word KWYJIBO, defining it as a "balding North American ape with a small chin". KWYJIBO isn’t permitted in tournament play, but it and other Springfield-specific words are allowed in the special Simpsons-themed edition. In this version the tiles are yellow and the board is shaped like Homer Simpson.

T is for Tiles. The original carved wooden tiles were changed to flat plastic tiles during the 1950s so that players couldn’t feel for high-scoring letters when they drew new tiles from the bag. For that nostalgic touch, you can still buy handmade wooden tiles from crafts website Etsy, and the really ostentatious can pick up a set of 24-carat gold-plated pieces from the Franklin Mint. The collectable kings’ luxury edition also features a walnut case and a rotating, leather-coated board.

U is for Underwater. In 1995 a game of Underwater Scrabble was played in a swimming pool at Portsmouth University in aid of Children In Need. Special laminated boards were used and the tiles had lead weights attached. In 2005 a pair of scuba divers sank even lower, playing at a table 20 metres under the Tasman Sea accompanied by an adjudicator, two rescue divers and several “slghtly bemused” sharks.

V is for Values. In 2013, American Scrabble player Joshua Lewis devised a software program called Valett which recalculated 14 of the 26 tile values - including dropping the iconic Z from 10 to six points - based on the words in the current Scrabble dictionary. Back in 1930, Alfred Butts had used an equally scientific if less computerised method of deciding tile values - he counted how many times letters appeared on the front page of the New York Times.

W is for Welsh. The Welsh edition, launched in 2005, contains individual tiles for the language’s characteristic LL, TH and DD sounds. There is no Z or Q in Welsh, so two other combinations, NG and RH, constitute the game’s 10-point tiles.

X is for X-treme. While most games are played over the time-honoured 15x15 board, in North America a version called Super Scrabble is played on a 21x21 board with 200 tiles and quadruple-word and -letter squares. Us Brits went one better though - in 1998 the Army and the Navy played a game on the Wembley Stadium pitch. The board measured 900 square metres and each two-metre-square tile had to be put in place by two people. For the record, the Navy won.

Y is for Youngsters. The colourful Scrabble Junior introduces children to the game through colourful words and pictures and a simpler scoring system. We’ve got a feeling Alan Saldanha was playing the adult version when he became UK champion aged 15 in 1993, although he’s not the most competitive junior player around - a five-year-old boy once phoned Leicester police to complain his sister was cheating at Scrabble.

Z is for Za, an acceptable slang term for ‘pizza’ and a great way of getting rid of spare letters late on in a game. Other handy two-letter words are ‘Aa’, a type of volcanic rock, ‘Al’, an East Indian tree and ‘Oe’, a whirlwind in the Faeroe Islands.