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Bitcoin Ordinals

The Bitcoin Ordinal Glossary: 12 Terms You Need to Know

Want to understand Bitcoin Ordinals? Here are 12 terms you need to know.
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Since its inception in December, the Ordinal protocol has brought a surge of new interest in building on the Bitcoin network — from bridges, fungible tokens, and runes to even sovereign roll-ups. It has also shed new light on how Bitcoin upgrades like Taproot and Segregated Witness (SegWit) can contribute to a rich digital asset ecosystem on Bitcoin. Ordinal NFTs have reached 35 million in inscriptions and over 60 million in fees, at the time of writing.

The Ordinal protocol has evolved to meet this growing demand on the Bitcoin blockchain. And as with any new technology, non-fungible token (NFT) collectors, artists and users of Bitcoin wallets like Leather need to learn a whole new set of terms and phrases to keep up with important Ordinal trends.

In this article, we’ll break down the common concepts in the Ordinal theory and get you up to date with all the latest innovations in the Bitcoin space. 

The Bitcoin Ordinal Glossary: Here's What You Need to Know About Ordinal Inscriptions


Inscriptions, or Ordinal NFTs, are digital artifacts — completely on-chain secure digital objects permanently stored on Bitcoin. Made possible by Ordinal theory (introduced by Casey Rodarmor), inscriptions essentially attach data such as text, image, or even videos to numbered satoshis, the smallest unit of Bitcoin on a block. Inscription data is stored in the witness field of a Bitcoin transaction, and artists pay a fee for every file they store.

Inscription Numbers

Along with an ID, every inscription on the Bitcoin blockchain is assigned a unique number based on the order and time it was added to the network. The first genesis inscription — or inscription 0 — is a black and white skull inscribed by Casey on December 14. Three days later, the community inscribed the second Ordinal NFT ever. 

Lower inscription numbers have achieved a collectible status — with communities forming around numbers less than 10, 100, 10K, and 100K. The premise is that the lower the Ordinal number, the earlier you are to the entire ecosystem. Early adopters (like those building the application infrastructure on Bitcoin) are always awarded in crypto — and Ordinals are no exception. 

Since inscription numbers are so relevant (and worth a lot) to the Ordinal community, there’s always discussion around these numbers.

Cursed Inscriptions

Although the term may sound ominous, cursed inscriptions are artifacts that did not receive an ordinal number due to a bug in the Ordinal protocol. In the May upgrade to the protocol, these cursed inscriptions were identified and assigned a negative number. 

Cursed inscriptions weren't initially indexed on Ordinal explorers or available with Bitcoin wallets, but have now been accommodated by major explorers and wallets. As of writing, over 80,000 cursed inscriptions now exist on Bitcoin. 

While Casey has proposed an eventual change to assigning new “cursed” inscriptions a positive number and turning them “blessed”, the actual block where this change will happen is still uncertain. 

Recursive Inscriptions

Recursive inscriptions are self-referential data structures in that each inscription can point to another inscription on the blockchain. By doing so, each inscription can technically cross the 4 MB storage limitation set by the Bitcoin blockchain while reducing transaction costs. This allows developers to create a chain of inter-connected data on the Bitcoin blockchain, useful in creating games, generative art, and so much more.

The use cases for recursive inscriptions are still evolving — yet they mark the ability to create more complex data structures within the Bitcoin blockchain's security. 


BRC-20 are fungible tokens on the Bitcoin blockchain that use text-based Ordinal inscriptions instead of smart contracts. Each BRC-20 token is a JSON Ordinal inscription containing token contracts that allow the minting and transfer of fungible tokens.


The BRC-721E token standard allows NFT projects to migrate collections from other blockchains like Ethereum and Polygon via a one-way bridge. This is done through “tele-burning”, which is the act of destroying an NFT by sending it to a pre-defined burn address and then re-minting it on the Bitcoin blockchain. Reminting is done through the Bitcoin Milady bridge. Once the NFT is reminted, the smart contract on the origin chain points to the new inscription on the Bitcoin blockchain.


Simply put, your Bitcoin wallet balance is made of multiple UTXOs, short for Unspent Transaction Outputs. 

Every Bitcoin transaction has an input and an output — the input is what you intend to send to the receiver, and the output is the remainder minus the miner’s fee. UTXOs keep track of all of your past Bitcoin transactions and contain each sat that is returned to you. 

UTXOs are essentially a bunch of sats that are linked to your wallet’s private key — including sats that have inscriptions on them.

Domain names

Domain names are the Ordinal-powered standardized names with TLDs such as .sats, .btc, .magic etc. On Bitcoin, domain names can be claimed and can be pointed to virtually anywhere. Claiming a domain requires you to be the first to inscribe it — after which all other claims are invalid.


Released in September 2023, Parent-child inscriptions act as a way to link the ownership of two or more inscription collections together. The root inscription acts as the “parent” from which the “child" inscriptions are derived. Child inscriptions can also be a parent for future inscriptions, creating a very interesting range of possibilities. For instance, parent-child inscriptions can represent a trilogy of books, whereas grandchildren can signify spin-offs from that series. 


Think of envelopes as wrappers around specific code that identify what that code does. In case of inscriptions, envelopes help us identify which witness data might be an inscription. They also enable an inscription to be broken into smaller parts to fit the size limit specified by each sat and still easily link them back to the larger inscription. Envelopes typically start with a series of opcode sequences i.e OP_FALSE, OP_IF … OP_ENDIF within which inscription data and metadata are pushed via OP_PUSH sequences. 

Envelopes have the potential to be used beyond Ordinals and inscriptions as well, specifically in tracking BRC-20 tokens.


Reinscription is a new, groundbreaking Ordinal technology released on September 11th, 2023, which allows Ordinal owners to re-inscribe existing satoshis with additional data. The new data is put in an array with the existing data (provided it is under the overall storage limit). Each reinscription appears in a chronological order.

Reinscription, combined with recursion, allows users to access infinite possibilities on a single satoshi, such as dynamic NFTs, version control, and so much more.

Sat Rarity

Similar to rarity on blockchains like Ethereum, sat rarity associates special meaning to specific satoshis, often due to historical or symbolic significance. The most common rarity index is the Rodarmor rarity index. This index assigns significance to particular sats based on their placement in the specific Bitcoin blocks. Here’s how it looks:

  • Uncommon - The first sat of any Bitcoin block
  • Rare - The first sat of a new Bitcoin block after a difficulty adjustment
  • Epic - The first sat in a Bitcoin block after a halving event
  • Legendary - The first sat of a Bitcoin block which went through both a halving and difficulty adjustment.
  • Mythic - The first sat in the Ordinal genesis block mined by Rodarmor.

Rarity and value often depend on the Ordinal buyer and are subject to many methodologies. Other rarity notations have also evolved, where people assign significance to blocks of a certain number or sat names. Many people even “hunt” rare sats to attach their inscriptions to increase the overall valuation.

The Future of Digital Artifacts, Inscriptions and Bitcoin NFTs 

With the rise of Ordinals, Bitcoin has become one of the top three blockchain hubs for NFT trading and minting. As the Ordinal protocol economy matures, the Bitcoin blockchain is set to see even more innovation surrounding this new technology. We’re already seeing Ordinal automation, liquid funds investing in innovative projects, and Ordinal-specific conferences taking center stage.

The journey for digital artifacts on Bitcoin is just beginning — and the sustained momentum for Ordinals and associated projects shows that the future is bright.