Ordinals

Casey Rodarmor's January 2023 protocol for numbering individual satoshis (the 100,000,000th of a Bitcoin) and inscribing arbitrary data (images, text, JSON) onto them. Inscriptions live in Bitcoin's witness data — content is embedded directly in the blockchain, not off-chain. Within months of launch, Ordinals grew to billions in trading volume. The successor protocol Runes (April 2024) is more efficient for fungible tokens.