A transaction confirmation level achieved when 66.7%+ of total stake has voted on the slot, typically within ~400ms. Optimistic confirmation provides high probability of finality without waiting for full root depth. It corresponds to the 'confirmed' commitment level in RPC queries.
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A transaction confirmation level achieved when 66.7%+ of total stake has voted on the slot, typically within ~400ms. Optimistic confirmation provides high probability of finality without waiting for full root depth. It corresponds to the 'confirmed' commitment level in RPC queries.
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Think of it as part of the chain machinery that keeps ordering, execution, or consensus moving.
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Consensus, leader rotation, slots, epochs, and the runtime.
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Optimistic Confirmation (optimistic-confirmation) Category: Core Protocol Definition: A transaction confirmation level achieved when 66.7%+ of total stake has voted on the slot, typically within ~400ms. Optimistic confirmation provides high probability of finality without waiting for full root depth. It corresponds to the 'confirmed' commitment level in RPC queries. Related: Confirmation, Finality
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A vote by a validator on a block, weighted by the validator's stake. The more stake-weighted confirmations a slot receives, the higher the confidence it will be finalized. RPC methods accept commitment levels (processed, confirmed, finalized) to specify the required confirmation threshold.
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.
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A vote by a validator on a block, weighted by the validator's stake. The more stake-weighted confirmations a slot receives, the higher the confidence it will be finalized. RPC methods accept commitment levels (processed, confirmed, finalized) to specify the required confirmation threshold.
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A vote by a validator on a block, weighted by the validator's stake. The more stake-weighted confirmations a slot receives, the higher the confidence it will be finalized. RPC methods accept commitment levels (processed, confirmed, finalized) to specify the required confirmation threshold.
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.
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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.
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).
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.
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.