Noah Webster’s book contained seventy thousand words, of which twelve thousand had never appeared in a published dictionary before. As a spelling reformer, Webster believed that English spelling rules were unnecessarily complex, so his dictionary introduced American English spellings, replacing colour with color, substituting wagon for waggon, and printing center instead of centre. He also added American words, like skunk and squash, that did not appear in British dictionaries. At the age of seventy, Webster published his dictionary in 1828, registering the copyright on April 14. Webster did all this in an effort to standardize the American language.