In the early 18th century, English spelling was notstandardized.Differences became noticeable(明显的，显著的)after thepublishing of influential dictionaries.Current British English spellingsfollow，for the most part,those of Samuel Johnson's Dictionary of theEnglish Language (1755).Many of the new characteristic AmericanEnglish spellings were introduced,although not,for the most part,created,by Noah Webster in his American Dictionary of the EnglishLanguage of 1828.

Webster was a strong proponent(倡导者)of spelling reform forreasons both philological and nationalistic.Many spelling changesproposed in the US by Webster himself，and in the early 20th century bythe Simplified Spelling Board,never caught on.Among the advocates ofspelling reform in England,the influences of those who preferred the Norman (or Anglo-French) spellings of certain words proveddecisive.Subsequent spelling adjustments in the UK had little effect onpresent-day US spelling , and vice versa(反之亦然). While in many casesAmerican English deviated(偏离;脱离)in the 19th century frommainstream British spelling,on the other hand it has also often retained(保留)older forms.

The spelling systems of Commonwealth countries，for the mostpart,closely resemble (像)the British system.In Canada,however，whilemost spelling is"British”，many “American”spellings are alsoused.Additional information on Canadian and Australian spelling isprovided throughout the article.