Many of the differences between American and British English date back to a time when spelling standards had not yet developed. For instance, some spellings seen as "American" today were once commonly used in Britain and some spellings seen as "British" were once commonly used in the United States. A "British standard" began to emerge following the 1755 publication of Samuel Johnson's A Dictionary of the English Language, and an "American standard" started following the work of Noah Webster and in particular his An American Dictionary of the English Language, first published in 1828.