Cliffs Notes are the invention of Clifton Hillegass. Hillegass, a book salesman from Nebraska, put out the first Cliffs Notes in 1958. The idea for Cliffs Notes came from Toronto, Canada, where another enterprising book seller, Jack Cole, was already producing small study guides which he called "Cole's Notes". The first series of booklets concentrated on Shakespeare's plays.

Cliffs Notes are currently put out by IDG Books (the company that also puts out the X for Dummies series), who bought Clifton Hillegass' company in 1998.

Currently, the best selling Cliffs Notes at amazon.com are:

  1. A Separate Peace, John Knowles.
  2. The Catcher in the Rye, J. D. Salinger.
  3. Frankenstein, Mary Shelley.
  4. Fahrenheit 451, Ray Bradbury.
  5. Great Expectations, Charles Dickens.