Spaced repetition is a learning technique where you review information at strategically increasing intervals over time. Instead of cramming, you revisit material just as you're about to forget it.

This combats the forgetting curve — our natural tendency to lose information quickly after first encountering it. The key insight is that each time you successfully recall a piece of information, the memory trace gets stronger, and the interval until your next review grows longer.

It's extremely efficient because algorithms (or your own schedule) push easy material further into the future while bringing difficult material back sooner. This means you spend your time where it's actually needed.

Spaced repetition works best when paired with Active Recall. Active recall defines how you study (testing yourself), while spaced repetition defines when you study (at optimal intervals). Together, they form one of the most evidence-backed learning strategies available.

Common tools that implement this include Anki, RemNote, and SuperMemo.