It's one of the first things we learn as children, the building blocks of our language and the common currency of most of the Western world. But, like a cryptic crossword riddle, its origins are a puzzle. Several thousand years after people first wrote down the sounds they used when speaking, men and women of letters are still divided over how they evolved.
Most agree that the eastern Mediterranean, Semitic civilisation provided the prototype for the Latin alphabet we use today. Inscriptions discovered in present-day Palestine show that people living there in about 1800bc had developed a system of consonants - possibly derived from Egyptian hieroglyphics - but so far removed from ours that no one has ever fully deciphered them.
By the 14th century bc the Syrians had invented a 30-letter cuneiform, or wedge-shaped, alphabet, and graffiti etched into the staircase of an ancient Israeli palace confirms that the order of the 22-letter Hebrew alphabet has not chnged since the seventh century bc. Around the same time, the Greeks added vowels to the Semitic alphabet, but not until the fourth century bc were the many variations used on different islands standardised into the 26-character set - the first two of which give the alphabet its name.
The Cyrillic alphabet derived from this and is still used in Slavic countries, but the more mystical, Middle Age runic and ogham alphabets used by north Europeans and Celts respectively are long since extinct.
In the 17th century, a certain Charles Butler tried to introduce new letters for oo, ee, ph, ch and wh, and in the 1940s the playwright George Bernard Shaw championed a 40-letter collection, but our alphabet has remained largely unchanged for 300 years.
Sixties and seventies schoolkids who struggled with theirs will remember the initial teaching alphabet, the mangled 40-letter phonetic version that was supposed to make reading easier. And while beginners - called abecedarians - continue to learn their ABC by rote and association, more advanced wits have come up with their own version: "Ay for 'Orses, Beef or Mutton, C for Yourself... "