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A Bitcoin soft fork activated in August 2017 (BIP 141) that separates transaction signature data (witness) from the transaction body, fixing transaction malleability and increasing effective block capacity from 1 MB to approximately 4 MB via a weight unit system. SegWit introduced a versioned witness program structure that enabled future upgrades like Taproot without additional soft forks. It was a prerequisite for the Lightning Network's secure operation.

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SegWit (Segregated Witness) (segwit)
Category: Blockchain General
Definition: A Bitcoin soft fork activated in August 2017 (BIP 141) that separates transaction signature data (witness) from the transaction body, fixing transaction malleability and increasing effective block capacity from 1 MB to approximately 4 MB via a weight unit system. SegWit introduced a versioned witness program structure that enabled future upgrades like Taproot without additional soft forks. It was a prerequisite for the Lightning Network's secure operation.
Aliases: Segregated Witness, BIP 141
Related: Bitcoin, Taproot, Lightning Network

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Branch

Bitcoin

The first decentralized cryptocurrency network, launched in 2009 by the pseudonymous Satoshi Nakamoto, using a Proof-of-Work consensus mechanism and a UTXO-based transaction model. Bitcoin's protocol enforces a fixed supply cap of 21 million BTC, with new coins issued through mining block rewards that halve approximately every four years. It serves as both a peer-to-peer electronic cash system and a store of value, with its scripting language enabling basic programmability such as multisig and timelocks.

Proof of Work (PoW)UTXO Model

Open term

Branch

Taproot

A Bitcoin soft fork activated in November 2021 (BIPs 340-342) introducing Schnorr signatures for efficient key/signature aggregation, MAST (Merkelized Abstract Syntax Trees) for committing complex spending conditions where only the exercised branch is revealed on-chain, and Tapscript extending Bitcoin Script with new opcodes. Taproot makes complex transactions (multisig, timelocks, conditional spending) indistinguishable from simple single-key transactions, improving privacy and efficiency.

Bitcoin Script Bitcoin Ordinals

Open term

Branch

Lightning Network

A Layer 2 payment channel network built on Bitcoin that enables near-instant, low-cost transactions by conducting most activity off-chain. Two parties open a channel by locking BTC in a multisig transaction, then exchange signed commitment transactions off-chain; only the opening and closing transactions are broadcast on-chain. Payments can be routed across multiple channels using Hash Time-Locked Contracts (HTLCs), enabling trustless multi-hop transfers.

Bitcoin Layer 2 Layer 2 (L2)

Open term

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Blockchain General

Bitcoin

The first decentralized cryptocurrency network, launched in 2009 by the pseudonymous Satoshi Nakamoto, using a Proof-of-Work consensus mechanism and a UTXO-based transaction model. Bitcoin's protocol enforces a fixed supply cap of 21 million BTC, with new coins issued through mining block rewards that halve approximately every four years. It serves as both a peer-to-peer electronic cash system and a store of value, with its scripting language enabling basic programmability such as multisig and timelocks.

Open term

Blockchain General

Taproot

A Bitcoin soft fork activated in November 2021 (BIPs 340-342) introducing Schnorr signatures for efficient key/signature aggregation, MAST (Merkelized Abstract Syntax Trees) for committing complex spending conditions where only the exercised branch is revealed on-chain, and Tapscript extending Bitcoin Script with new opcodes. Taproot makes complex transactions (multisig, timelocks, conditional spending) indistinguishable from simple single-key transactions, improving privacy and efficiency.

Open term

Blockchain General

Lightning Network

A Layer 2 payment channel network built on Bitcoin that enables near-instant, low-cost transactions by conducting most activity off-chain. Two parties open a channel by locking BTC in a multisig transaction, then exchange signed commitment transactions off-chain; only the opening and closing transactions are broadcast on-chain. Payments can be routed across multiple channels using Hash Time-Locked Contracts (HTLCs), enabling trustless multi-hop transfers.

Open term

Blockchain General

Sequencer

The entity responsible for ordering, batching, and submitting transactions in a Layer 2 rollup. Most rollups currently use a single centralized sequencer operated by the rollup team. Decentralized and shared sequencer designs (Espresso, Astria) distribute this power across a network of operators, enabling cross-rollup atomic composability and reducing single points of failure.

Open term

Related terms

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Blockchain Generalbitcoin

Bitcoin

The first decentralized cryptocurrency network, launched in 2009 by the pseudonymous Satoshi Nakamoto, using a Proof-of-Work consensus mechanism and a UTXO-based transaction model. Bitcoin's protocol enforces a fixed supply cap of 21 million BTC, with new coins issued through mining block rewards that halve approximately every four years. It serves as both a peer-to-peer electronic cash system and a store of value, with its scripting language enabling basic programmability such as multisig and timelocks.

Open term

Blockchain Generaltaproot

Taproot

A Bitcoin soft fork activated in November 2021 (BIPs 340-342) introducing Schnorr signatures for efficient key/signature aggregation, MAST (Merkelized Abstract Syntax Trees) for committing complex spending conditions where only the exercised branch is revealed on-chain, and Tapscript extending Bitcoin Script with new opcodes. Taproot makes complex transactions (multisig, timelocks, conditional spending) indistinguishable from simple single-key transactions, improving privacy and efficiency.

Open term

Blockchain Generallightning-network

Lightning Network

A Layer 2 payment channel network built on Bitcoin that enables near-instant, low-cost transactions by conducting most activity off-chain. Two parties open a channel by locking BTC in a multisig transaction, then exchange signed commitment transactions off-chain; only the opening and closing transactions are broadcast on-chain. Payments can be routed across multiple channels using Hash Time-Locked Contracts (HTLCs), enabling trustless multi-hop transfers.

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