The term “commercial dictionary” comprises numerous species of dictionary marketed to the public or identified cohorts of the public. Colloquial references to “the dictionary” likely refer to a commercial dictionary. English dictionaries began to develop in Britain along with the development of printing and by the end of the 18th century, the idea of the dictionary as a language authority of practical use to the ordinary person was well established in England. In the US, development of dictionaries began soon after colonial times, thanks largely to Noah Webster. The market for commercial dictionaries flourished and diversified in the 19th and 20th centuries, resulting in a robust and competitive market for them in the US and the UK, which remained beacons of English lexicographic endeavor. With the arrival of computers in the mid−20th century, the commercial dictionary began its slow decline in prominence and authority, owing to the widespread availability of dictionary definitions online via computers and hand-held devices. Today, very few names in publishing are associated with commercial dictionaries and all publishers still in the market have other means of profiting from dictionary data.