What is "retrieval practice" (also called active recall or the testing effect)?

Deliberately pulling information OUT of your memory — self-quizzing — instead of passively putting it back IN by re-reading.

Re-reading, highlighting, and copying notes feel productive but mostly move your eyes over already-familiar words. Retrieval practice means closing the book and forcing yourself to reconstruct the answer: flashcards, free recall ("brain dumps"), turning a heading into a question and answering it, low-stakes quizzes.

The distinction is direction of travel: encoding (in) versus retrieval (out). This technique is the single highest-leverage thing the evidence supports — and it's exactly what every flashcard and duel in this app makes you do.