[What follows is a massive simplification of a very involved topic; I’d really recommend looking at the resources here if you’re after more detail.]
English is written using a phonetic system, in that the symbols (letters) are used to represent sounds directly, but it uses a complicated set of conventions to do so: you cannot, as people used to do long ago, choose your own way of representing the sounds (or at least, you could but you would generally encounter confusion, surprise, and general disapproval if you did – at least in formal written contexts). These conventions include the use of the same letters and combinations of letters for different sounds (go, to, top) and different letters and combinations of letters for the same sounds (my, lie, tiny). There are complex historical reasons for this.
It’s important to remember, though, that although our system of writing is based on a phonetic principle – each symbol represents a sound, not a meaning (as would be the case, for instance, if we ‘wrote’ by drawing a picture of each thing), it is nevertheless inexact. Many different languages use the Latin alphabet, but each one of them relates to it slightly differently, and in each language (in each accent, too), the letter symbols represent related, but different, sounds.
So at the level of the individual letter, the kind of relationship of visual symbol to heard sound is basically the same, but the actual sound communicated varies according to the language concerned. This means that anyone who speaks more than one language has to know the different ‘meaning’ of each letter, in terms of the sound it represents for each of their different languages.
How did English end up with a system of symbols which doesn’t really fit the sounds of the language?
The Latin alphabet emerged around the Mediterranean well over two thousand years ago, for the transcription of languages which differ significantly from English.
This means that in order to represent the sounds of English, the letter-symbols need to be used creatively, and the sound intended is not transparent for a reader. Readers of English are always doing a sort of mental juggling act with the sound possibilities.
Prior to the use of the Latin alphabet in England, Old English sometimes used the ‘futhark’ alphabet, a form of alphabet based on runic symbols which it had in common with other Germanic languages.
It is really interesting, I think, that the English version of the futhark, which evolved form the 5th century onwards, contained more runes (33) than the ‘Elder Futhark’, which only contained 24. So Old English already had a need for more sounds than its sister languages elsewhere.
The people of Anglo-Saxon England obviously felt free to invent new letters where they needed them.
With the influence of Christianity came the gradual switch to the Latin alphabet, strengthened greatly by the Normans’ use of it from 1066 onwards.
It is fascinating, too, to look at the sounds of Old English as represented in the Latin alphabet. There is a very similar number of sounds to that in English today, though many of the sounds themselves have changed a bit over the centuries.
It’s also obvious that people in Anglo-Saxon England were faced by the same problem that we face today: they had more sounds in their language than letters in the Latin alphabet. They used the same solution: combinations of letters to represent the ‘extra’ sounds.
Other languages have solved this problem with ‘diacritics‘, which is in many ways much more convenient and logical. But hey ho.
So although the language that we speak now is very different from Old English, being a combination of that language with Norman French (which soon evolved its own English branch called ‘Anglo-Norman‘) plus lots of more modern borrowings and newly invented words, there is an underlying pattern of the number of sounds which we seem to need!
‘Middle English’ (the language spoken in England during the Middle Ages) seems to have used a similar number of sounds, too.
Philip Durkin (who properly knows what he’s talking about rather than being a dabbler like me) provides an outline of the features of Middle English here.
However. Although English today has a similar number of sounds to Old English, it has many more ways of writing them, because our orthography, like our language, is a blending of Old English and Norman French, plus some added Viking, Latin and Greek for good measure.
There’s a summary of the change from Middle English to Modern English here (by the ever fabulous and very lovely Edmund Weiner, who gave me my first job at the OED, a very long time ago.).
[To be continued…!]