Spaced repetition is a memorization technique that involves the scheduling of study sessions according to an algorithm optimized for efficient long-term retention of the learned material.

Further reading

Branwen, Gwern (2009) Spaced repetition for efficient learning, Gwern.net, March 11 (updated 17 May 2019).

Nielsen, Michael (2018) Augmenting long-term memory, Augmenting Cognition, July.