Inscription

An inscription is a piece of data — an image, text, or other file — permanently embedded in a Bitcoin transaction and attached to a specific satoshi under the Ordinals protocol. Inscribing is Bitcoin's equivalent of minting an NFT: the content is written into the blockchain itself, and ownership follows whoever controls the inscribed satoshi.

Technically, the file is placed in the witness portion of a Bitcoin transaction using script features enabled by the Taproot upgrade. Once mined into a block, the data is part of Bitcoin's permanent record: every full node stores it, and it cannot be edited or deleted. For example, an artist can inscribe a small image, and a collector who later receives that satoshi owns the artwork with no external dependencies — no metadata server, no IPFS link that might break.

This full on-chain storage is the key difference from most Ethereum NFTs, where the token is on-chain but the media usually lives elsewhere. The trade-off is size and cost: block space is scarce, so inscriptions are limited to a few hundred kilobytes in practice and large files are expensive to inscribe, with fees rising sharply during periods of high demand. Text inscriptions following the BRC-20 convention are also used to create fungible tokens on Bitcoin.