Anki

Anki is a flashcard program that schedules reviews using spaced repetition, showing you each card just before you would forget it. That makes it very efficient for memorizing large amounts of material. It is highly customizable, supports images, audio and formulas, and has thousands of community add-ons and shared decks. Many add-ons bring AI to generate cards from notes. Anki is free and open source on desktop and Android, with a paid iOS app. It is a favorite for medical school, languages and anything fact-heavy.