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Plain meaning

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An experimental fungible token standard on Bitcoin using Ordinals inscriptions in JSON format to deploy, mint, and transfer tokens. BRC-20 tokens store state in inscription data and require off-chain indexers to track balances, as Bitcoin has no native token state concept. The standard gained significant adoption in 2023-2024 but creates excessive junk UTXOs, leading to the development of the UTXO-native Runes protocol as an alternative.

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BRC-20 (brc-20)
Category: Blockchain General
Definition: An experimental fungible token standard on Bitcoin using Ordinals inscriptions in JSON format to deploy, mint, and transfer tokens. BRC-20 tokens store state in inscription data and require off-chain indexers to track balances, as Bitcoin has no native token state concept. The standard gained significant adoption in 2023-2024 but creates excessive junk UTXOs, leading to the development of the UTXO-native Runes protocol as an alternative.
Aliases: BRC20
Related: Bitcoin Ordinals, Runes, UTXO Model

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Branch

Bitcoin Ordinals

A protocol created by Casey Rodarmor in January 2023 that assigns a unique serial number (ordinal) to each individual satoshi based on mining order, enabling satoshis to carry arbitrary data (inscriptions) stored in Taproot witness data. Inscriptions can contain images, text, HTML, or other media up to the ~4 MB block weight limit, creating non-fungible digital artifacts natively on Bitcoin. Over 63 million inscriptions were created by early 2024.

Bitcoin Taproot

Open term

Branch

Runes

A Bitcoin fungible token protocol created by Casey Rodarmor that launched at block 840,000 on April 20, 2024, coinciding with the fourth Bitcoin halving. Unlike BRC-20, Runes is UTXO-native, using OP_RETURN to store token data directly in transaction outputs without creating junk UTXOs. The protocol allows multiple token transfers in a single transaction and briefly accounted for over 80% of Bitcoin transactions in its first days.

Bitcoin Halving

Open term

Branch

UTXO Model

The accounting model used by Bitcoin (and derived chains like Litecoin and Zcash) where balances are represented as a set of unspent transaction outputs rather than account balances. Each transaction consumes one or more UTXOs as inputs and creates new UTXOs as outputs; the difference between input and output values constitutes the transaction fee. The UTXO model enables natural parallelism and simple verification but makes stateful smart contracts more complex compared to account-based models like Ethereum or Solana.

Bitcoin Script

Open term

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Blockchain General

Bitcoin Ordinals

A protocol created by Casey Rodarmor in January 2023 that assigns a unique serial number (ordinal) to each individual satoshi based on mining order, enabling satoshis to carry arbitrary data (inscriptions) stored in Taproot witness data. Inscriptions can contain images, text, HTML, or other media up to the ~4 MB block weight limit, creating non-fungible digital artifacts natively on Bitcoin. Over 63 million inscriptions were created by early 2024.

Open term

Blockchain General

Runes

A Bitcoin fungible token protocol created by Casey Rodarmor that launched at block 840,000 on April 20, 2024, coinciding with the fourth Bitcoin halving. Unlike BRC-20, Runes is UTXO-native, using OP_RETURN to store token data directly in transaction outputs without creating junk UTXOs. The protocol allows multiple token transfers in a single transaction and briefly accounted for over 80% of Bitcoin transactions in its first days.

Open term

Blockchain General

UTXO Model

The accounting model used by Bitcoin (and derived chains like Litecoin and Zcash) where balances are represented as a set of unspent transaction outputs rather than account balances. Each transaction consumes one or more UTXOs as inputs and creates new UTXOs as outputs; the difference between input and output values constitutes the transaction fee. The UTXO model enables natural parallelism and simple verification but makes stateful smart contracts more complex compared to account-based models like Ethereum or Solana.

Open term

Blockchain General

Bridge (Cross-Chain)

A protocol that enables transferring assets or data between different blockchains. Bridges use mechanisms like lock-and-mint (lock on source, mint wrapped on destination), liquidity pools, or relay networks. Bridges are high-value attack targets—Wormhole ($320M, 2022), Ronin ($625M, 2022). Wormhole is Solana's primary bridge to Ethereum and other chains.

Open term

Related terms

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Blockchain Generalbitcoin-ordinals

Bitcoin Ordinals

A protocol created by Casey Rodarmor in January 2023 that assigns a unique serial number (ordinal) to each individual satoshi based on mining order, enabling satoshis to carry arbitrary data (inscriptions) stored in Taproot witness data. Inscriptions can contain images, text, HTML, or other media up to the ~4 MB block weight limit, creating non-fungible digital artifacts natively on Bitcoin. Over 63 million inscriptions were created by early 2024.

Open term

Blockchain Generalrunes-protocol

Runes

A Bitcoin fungible token protocol created by Casey Rodarmor that launched at block 840,000 on April 20, 2024, coinciding with the fourth Bitcoin halving. Unlike BRC-20, Runes is UTXO-native, using OP_RETURN to store token data directly in transaction outputs without creating junk UTXOs. The protocol allows multiple token transfers in a single transaction and briefly accounted for over 80% of Bitcoin transactions in its first days.

Open term

Blockchain Generalutxo-model

UTXO Model

The accounting model used by Bitcoin (and derived chains like Litecoin and Zcash) where balances are represented as a set of unspent transaction outputs rather than account balances. Each transaction consumes one or more UTXOs as inputs and creates new UTXOs as outputs; the difference between input and output values constitutes the transaction fee. The UTXO model enables natural parallelism and simple verification but makes stateful smart contracts more complex compared to account-based models like Ethereum or Solana.

Open term

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Blockchain General

Blockchain

A distributed, append-only ledger that records transactions in cryptographically linked blocks. Each block contains a hash of the previous block, forming an immutable chain. Nodes in the network maintain copies of the ledger and reach agreement through consensus mechanisms. Blockchains enable trustless, decentralized record-keeping without a central authority.

Open term

Blockchain General

Consensus Mechanism

The protocol by which nodes in a distributed network agree on the current state of the ledger. Common mechanisms include Proof of Work (Bitcoin), Proof of Stake (Ethereum, Solana), and BFT variants. Consensus ensures all honest nodes converge on the same transaction history despite potential network delays or malicious actors.

Open term

Blockchain General

Proof of Stake (PoS)

A consensus mechanism where validators are selected to produce blocks based on the amount of cryptocurrency they have staked (locked) as collateral. PoS is energy-efficient compared to Proof of Work. Misbehaving validators risk losing their stake (slashing). Solana, Ethereum (post-Merge), Cosmos, and Cardano use PoS variants.

Open term

Blockchain General

Proof of Work (PoW)

A consensus mechanism where miners compete to solve computationally expensive puzzles to produce blocks and earn rewards. PoW provides strong security (51% attack resistance) but is energy-intensive. Bitcoin and pre-Merge Ethereum use PoW. The difficulty adjusts to maintain target block times regardless of total network hash power.

Open term