The literature study guides known as "Cliffs Notes" (often misspelled as "Cliff Notes") are so well-known as to be a cliche. Each guide is dedicated to a particular book, exploring the life of the author and the times during which the book was written, summarizing the plot, describing the characters, and exploring the themes and symbols in the book. For students, CliffNotes are seen as a shortcut to good grades; for serious teachers of literature, they are widely regarded as anathema.

The company which publishes CliffsNotes was founded by Clifton Hillegass (1918-1998) in 1958. It is now a division of John Wiley & Sons, Inc. Over the years, CliffsNotes has inspired a host of imitators. Meanwhile, CliffsNotes study guides have expanded their coverage into various other areas, including study guides for subjects like biology and chemistry, study guides for standardized tests, and various how-to guides for non-academic topics.