Wikipedia
Brainscape is a web and mobile education platform that allows students to study adaptive flashcards. The website and mobile application allow students, teachers, and corporate trainers to create (or upload) electronic flashcards, and to find flashcards created by other users and publishers around the world. Flashcards are all stored in the cloud and can be shared with groups of other learners.
Brainscape's most distinguishing characteristic is its flashcard repetition algorithm, called Confidence-Based Repetition (CBR). CBR is a personalized form of spaced repetition, in which the learner rates his/her confidence in each flashcard, on a scale of 1-5, which subsequently determines how frequently to repeat the flashcard. Lower-confidence items are repeated more frequently until the user upgrades his/her confidence rating, thereby creating an optimized study stream. Brainscape has published a white paper which cites over 800 academic studies proving the viability of the cognitive science research that it applies in its technology.