He supplied sample quotations to back up his definitions. People turned to Johnson's Dictionary to learn correct standards of written expression. In 1828, Noah Webster , a New England lexicographer and entrepreneur, published his American Dictionary. Webster was so successful that his name is now in the public domain. Webster's is now a generic term for any American dictionary.
Dictionaries have a great impact on usage.
The OED was assembled in the 19th century through the efforts of a horde of volunteer contributors marshaled together by Sir James Murray, the formidable editor who saw the OED through most of its publication. A typical OED entry looks like the ones available at the Word of the Day site reachable through the OED prototype pages .