Who is William Strunk from Letters of E. B. White and what is their importance?

William Strunk was an English faculty member at Cornell University who became good friends with E.B. White. Strunk carried a little book of his pet peeves for good, clear writing that he shared with students. Years later, White revised and added material to Strunk's book, and it is published under both names as "The Elements of Style," a perennial bestseller.