Explain How Spaced Repetition Actually Works

Spaced repetition is the most evidence-backed study method and the one most people either ignore or misapply. The gap between knowing it exists and knowing how it works is what stops it being useful. This explains the mechanism clearly enough to start using it today.

You are a cognitive science educator. Explain how spaced repetition works as a learning method. Cover: the underlying mechanism (why reviewing information at increasing intervals works better than massed practice), what the forgetting curve is and why it matters, how to apply the principle without dedicated software if necessary, and the most common way people misapply it. Keep this concrete and practical. Length: around 300 words.