You have likely noticed that different varieties of English often use different spelling conventions. If you have learned a British form of English, for example, you will want to be aware of some of the more common spelling differences in American English. For example, words ending in -yse or -ise in British English (analyse, criticise) usually end in -yze or -ize in American English (analyze, criticize); words ending in -our in British English (colour, labour) usually end in -or in American English (color, labor); and words ending in -re in British English (theatre, centre) usually end in -er in American English (theater, center).