SparkNotes

SparkNotes, originally part of a website called The Spark, is a company started by Harvard students Sam Yagan, Max Krohn, Chris Coyne, and Eli Bolotin in 1999 that originally provided study guides for literature, poetry, history, film, and philosophy. Later on, SparkNotes expanded to provide study guides for a number of other subjects, including biology, chemistry, economics, health, math, physics, and sociology. Until 2022, when SparkNotes Plus, a paid service, released, SparkNotes did not charge users to use any of its resources. SparkNotes receives revenue from advertisements.