What is Ordinals?

A numbering scheme that gives every satoshi a serial number by mint order, allowing individual satoshis to be tracked and to carry arbitrary data inscribed in a Taproot witness.

It was published as ordinal theory with a reference implementation called ord, and it needs no change to Bitcoin itself: the protocol sees ordinary transactions, and the meaning lives in the software that interprets them. That is the part worth holding onto, because it explains both why it could not be stopped and why it carries no protocol-level guarantees.

Inscriptions consume block space like any other data, so heavy inscription activity raises fee rates for everyone using the network, including people simply moving coins.

How it works

Ordinal theory assigns each satoshi a number in the order it was mined, then tracks it through transactions using a first-in-first-out rule: the first satoshi into a transaction is the first satoshi out, into the first output. Nothing on chain records this. It is a convention that any indexer can apply to public data and reach the same answer.

Inscriptions build on that. Data is embedded in the witness portion of a Taproot spend, which the Taproot upgrade made practical by removing earlier limits on witness size. The data is attached to a specific satoshi, and moving that satoshi moves the inscription.

Two consequences follow. First, the content is fully on chain, not a pointer to a server, which is the main difference from most token-based collectibles. Second, it is stored in the witness, which is discounted in fee weight relative to other transaction data, though at scale it still competes for space.

Related schemes built on the same ideas include token standards that use inscriptions to represent fungible balances, and a later approach that encodes fungible tokens directly in Bitcoin transaction outputs.

Example

Illustrative sequence showing the fragility. You hold an inscribed satoshi in a wallet that understands ordinals, which keeps it separated from your ordinary balance.

You deposit the whole wallet balance to an exchange. The exchange credits you the Bitcoin amount and sweeps the coins into a pooled wallet, mixing that satoshi with everyone else's. The inscription still exists on chain and is still attached to a satoshi, but that satoshi is now somewhere in an exchange's cold storage and is not coming back. Nothing malfunctioned. The exchange accounts in Bitcoin, and one satoshi is the same as any other to it.

Why it matters when you buy

Two practical points. Buying Bitcoin normally has nothing to do with ordinals, but inscription activity is one reason network fees spike, which affects the cost of your withdrawals. And if you ever hold inscribed satoshis, they need a wallet that performs coin control, because a normal wallet or an exchange deposit will spend them as ordinary value. Per-network fee conditions are measured on the chain rankings, and withdrawal costs by venue are compared at the fee comparison.

Related terms

• taproot — the upgrade that made inscriptions practical
• satoshi — the unit being numbered
• network fee — what inscription activity drives up
• nft — the token-based equivalent elsewhere
• coin control — how to avoid spending one accidentally
• runes — the later fungible token approach

Questions

Do ordinals change Bitcoin?

No. They are an interpretation applied by software to ordinary transactions. Nodes that know nothing about ordinal theory validate the same blocks in the same way.

Can I buy ordinals on a normal exchange?

Generally no. They trade on dedicated marketplaces, and buying requires Bitcoin in a wallet that supports the standard rather than an exchange balance.

Why do people object to them?

Because inscriptions compete for block space with payments, raising fees for everyone. Others argue that fee-paying data is a legitimate use of an open market for block space. Both positions are held sincerely.