English has no single authority that decides spelling, and over the centuries the language settled into several standard varieties. The two that most writers meet are American and British English. Their differences are small (most words are spelled the same everywhere) but they are systematic, and mixing them in one document reads as a mistake.
Where the differences come from
Many American spellings go back to the lexicographer Noah Webster, who wanted a simpler, more regular spelling for the new country and promoted it in his dictionaries, above all An American Dictionary of the English Language (1828). Some of his proposals stuck, such as color, center and defense; others, like tung for tongue, never did. British spelling kept more of the forms inherited from French and Latin.
The main patterns
| Pattern | American | British |
|---|---|---|
| -or / -our | color, honor, favorite | colour, honour, favourite |
| -er / -re | center, theater, meter | centre, theatre, metre |
| -ize / -ise | organize, realize | organise, realise (or -ize, see below) |
| -yze / -yse | analyze, paralyze | analyse, paralyse |
| -se / -ce nouns | defense, offense, license | defence, offence, licence |
| doubled l | traveled, canceled, modeling | travelled, cancelled, modelling |
| -og / -ogue | catalog, dialog (both forms in use) | catalogue, dialogue |
A few pairs follow no pattern and simply have to be known: gray and grey, tire and tyre, curb and kerb, plow and plough, aluminum and aluminium (which differ in pronunciation too).
Words that change with their job
British English spells some nouns and verbs differently: a licence but to license, a doctor's practice but to practise the piano. American English uses license and practice for both. Similarly, British writers use programme for a television or events programme and program for software.
Oxford spelling and the other varieties
- Oxford spelling is British spelling with -ize endings: organization, realize, but still colour and analyse. Oxford University Press uses it, and so do many international organisations. Both -ise and -ize are correct British English.
- Canadian spelling mixes the two: colour and centre with the British, organize and tire with the Americans.
- Australian, New Zealand and South African English largely follow British spelling, with -ise the more common ending. (Australia's Labor Party, spelled the American way, is a well-known exception.)
Choosing a variety
Write for your readers: American spelling for an American audience, British for a British one. Where there is no obvious audience, follow your organisation's style guide, or simply keep the variety you started with. What matters is that one document does not say color in one paragraph and colour in the next.
How the spell checker helps
The Spell Checker offers six varieties of English: American, British, Australian, Canadian, New Zealand and South African. It checks spelling against the variety you choose, so with American English selected a British spelling such as colour is pointed out, and the other way round, which is the quickest way to make a document consistent. One thing to know: if you leave the language on automatic detection, English is checked as American English. For any other variety, pick it yourself before you check.