How spaced repetition works

Spaced repetition schedules each card based on how well you knew it last time. Cards you nail get pushed further into the future; cards you miss come back quickly until they stick.

This targets the "forgetting curve": reviewing a fact right before you would have forgotten it is the most efficient way to move it into long-term memory. You do not need to manage any of this — just rate your recall honestly and the scheduler handles the rest.