You know how you can "like" something on legacy social media? A "Zap" is like a like, but comes with real money attached. When you see content on Nostr that you love or found valuable, instead of just tapping a heart, you can send the person a Zap. Zaps are powered by Bitcoin! You can send a few pennies worth of bitcoin or a few dollars worth or more. This happens instantly. It goes directly from your wallet to their wallet. No middleman. No platform taking a cut. No follower counts needed. It's just humans sending value to other humans for content that they themselves found valuable.