The Oxford English Dictionary (OED) has its origins in early attempts in the 16th century to compile English words into dictionaries. Some key developments include Robert Cawdrey's 1604 dictionary, which was one of the first monolingual English dictionaries, and Samuel Johnson's 1755 dictionary, which included over 42,000 entries and set the standard. However, the most important and influential dictionary is considered to be the OED, which began in 1857 and continues to be revised on an ongoing basis, reflecting the inevitable changes in the English language over time.