Glossary OS

Plain meaning

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The mechanism for activating protocol changes on Solana's mainnet cluster. Each feature is identified by a unique pubkey and activated when validators representing a supermajority of stake signal support by creating a feature account. Feature gates control runtime behavior changes, new syscalls, parameter adjustments, and program upgrades. This system allows gradual, stake-weighted rollout of protocol changes without hard forks.

Mental model

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Think of it as part of the chain machinery that keeps ordering, execution, or consensus moving.

Technical context

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Consensus, leader rotation, slots, epochs, and the runtime.

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Feature Gate (feature-gate)
Category: Core Protocol
Definition: The mechanism for activating protocol changes on Solana's mainnet cluster. Each feature is identified by a unique pubkey and activated when validators representing a supermajority of stake signal support by creating a feature account. Feature gates control runtime behavior changes, new syscalls, parameter adjustments, and program upgrades. This system allows gradual, stake-weighted rollout of protocol changes without hard forks.
Related: Validator, SIMD (Solana Improvement Document), Runtime

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Concept graph

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Branch

Validator

A node that participates in the Solana network by validating transactions, voting on blocks, and (when selected as leader) producing new blocks. Validators run the Agave, Firedancer, or Jito client software, require significant hardware (128+ GB RAM, high-core CPU, NVMe SSD), and earn rewards from inflation and transaction fees.

Vote Account Stake

Open term

Branch

SIMD (Solana Improvement Document)

A formal specification document describing proposed and accepted changes to the Solana protocol, analogous to Ethereum's EIPs. SIMDs are categorized as Standard (Core, Networking, Interface) or Meta, and require supermajority validator stake-weighted voting (66.67%) to pass. Notable SIMDs include SIMD-33 (Timely Vote Credits), SIMD-123 (Block Revenue Sharing), SIMD-228 (Market-Based Emissions), and SIMD-326 (Alpenglow).

Consensus Mechanism Epoch

Open term

Branch

Runtime

The component of the SVM responsible for loading programs, enforcing account access rules (ownership, writability, signer checks), managing compute budgets, and executing transactions. The runtime ensures programs can only modify accounts they own, charges rent, and enforces the 10MB per-transaction account data limit.

Solana Virtual Machine (SVM)Sealevel

Open term

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Core Protocol

Validator

A node that participates in the Solana network by validating transactions, voting on blocks, and (when selected as leader) producing new blocks. Validators run the Agave, Firedancer, or Jito client software, require significant hardware (128+ GB RAM, high-core CPU, NVMe SSD), and earn rewards from inflation and transaction fees.

Open term

Core Protocol

SIMD (Solana Improvement Document)

A formal specification document describing proposed and accepted changes to the Solana protocol, analogous to Ethereum's EIPs. SIMDs are categorized as Standard (Core, Networking, Interface) or Meta, and require supermajority validator stake-weighted voting (66.67%) to pass. Notable SIMDs include SIMD-33 (Timely Vote Credits), SIMD-123 (Block Revenue Sharing), SIMD-228 (Market-Based Emissions), and SIMD-326 (Alpenglow).

Open term

Core Protocol

Runtime

The component of the SVM responsible for loading programs, enforcing account access rules (ownership, writability, signer checks), managing compute budgets, and executing transactions. The runtime ensures programs can only modify accounts they own, charges rent, and enforces the 10MB per-transaction account data limit.

Open term

Core Protocol

Finality

The guarantee that a transaction cannot be reversed. Solana offers two levels: optimistic confirmation (~400ms, 66.7%+ stake voted) and full finality (~12-13 seconds, 31+ confirmations rooted). Once a slot is rooted, its transactions are irreversible under the assumption that no more than 1/3 of stake is malicious.

Open term

Related terms

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Core Protocolvalidator

Validator

A node that participates in the Solana network by validating transactions, voting on blocks, and (when selected as leader) producing new blocks. Validators run the Agave, Firedancer, or Jito client software, require significant hardware (128+ GB RAM, high-core CPU, NVMe SSD), and earn rewards from inflation and transaction fees.

Open term

Core Protocolsimd

SIMD (Solana Improvement Document)

A formal specification document describing proposed and accepted changes to the Solana protocol, analogous to Ethereum's EIPs. SIMDs are categorized as Standard (Core, Networking, Interface) or Meta, and require supermajority validator stake-weighted voting (66.67%) to pass. Notable SIMDs include SIMD-33 (Timely Vote Credits), SIMD-123 (Block Revenue Sharing), SIMD-228 (Market-Based Emissions), and SIMD-326 (Alpenglow).

Open term

Core Protocolruntime

Runtime

The component of the SVM responsible for loading programs, enforcing account access rules (ownership, writability, signer checks), managing compute budgets, and executing transactions. The runtime ensures programs can only modify accounts they own, charges rent, and enforces the 10MB per-transaction account data limit.

Open term

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Core Protocol

Proof of History (PoH)

A clock mechanism that cryptographically proves the passage of time between events. PoH uses a sequential SHA-256 hash chain where each output becomes the next input, creating a verifiable ordering of events without requiring consensus. The leader produces ~400,000 hashes per slot (~400ms), and any validator can verify the sequence in parallel, enabling Solana's high throughput by removing the need for validators to agree on time.

Open term

Core Protocol

Tower BFT

Solana's custom BFT consensus algorithm built on top of Proof of History. Tower BFT uses PoH as a clock to reduce communication overhead in traditional PBFT from O(n²) to O(n). Validators vote on forks with exponentially increasing lockout periods—each consecutive vote doubles the lockout, making rollbacks progressively more expensive. A fork is finalized when it reaches supermajority (66.7%+ of stake).

Open term

Core Protocol

Slot

A time window during which a designated leader validator can produce a block. Each slot lasts approximately 400 milliseconds. Slots are numbered sequentially from genesis and grouped into epochs of 432,000 slots (~2-3 days). Not every slot produces a block—a skipped slot means the leader was offline or too slow.

Open term

Core Protocol

Block

A set of entries produced by a leader during a single slot. A block contains transactions bundled into entries, each with a PoH hash proving ordering. Blocks are broken into shreds for network propagation via Turbine. Maximum block size is limited by compute units (48M CU cap per block) rather than byte size.

Open term