The validator currently designated to produce blocks for a given slot, as determined by the leader schedule. The leader receives transactions via its TPU, orders them using Proof of History, executes them, and broadcasts the resulting block as shreds via Turbine. Each slot has exactly one assigned leader, and leaders rotate according to the stake-weighted schedule.
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The validator currently designated to produce blocks for a given slot, as determined by the leader schedule. The leader receives transactions via its TPU, orders them using Proof of History, executes them, and broadcasts the resulting block as shreds via Turbine. Each slot has exactly one assigned leader, and leaders rotate according to the stake-weighted schedule.
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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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Leader (leader) Category: Core Protocol Definition: The validator currently designated to produce blocks for a given slot, as determined by the leader schedule. The leader receives transactions via its TPU, orders them using Proof of History, executes them, and broadcasts the resulting block as shreds via Turbine. Each slot has exactly one assigned leader, and leaders rotate according to the stake-weighted schedule. Related: Leader Schedule, Slot, TPU (Transaction Processing Unit), Validator
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A deterministic mapping of slots to validators for an entire epoch, computed from stake weights. Validators with more stake are assigned proportionally more leader slots. The schedule is derived using a seed from the previous epoch's randomness, so all validators independently compute the same schedule without coordination.
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.
Transaction Processing Unit—the pipeline within a leader validator that ingests, verifies, and executes transactions. The TPU has stages: fetch (receive packets via QUIC), sigverify (verify Ed25519 signatures), banking (execute against current bank state), and broadcast (shred and send via Turbine). Non-leader validators forward transactions to the current leader's TPU.
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.
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A deterministic mapping of slots to validators for an entire epoch, computed from stake weights. Validators with more stake are assigned proportionally more leader slots. The schedule is derived using a seed from the previous epoch's randomness, so all validators independently compute the same schedule without coordination.
The complete ordered history of all transactions processed by the Solana cluster. The ledger is composed of sequential blocks (one per slot), each containing entries of transactions ordered by PoH. Validators store the ledger locally in Blockstore, and warehouse nodes or Bigtable archives provide long-term historical access.
The period during which a Tower BFT vote prevents a validator from switching to a competing fork. Lockouts double with each consecutive confirmation: vote depth 1 = 2-slot lockout, depth 2 = 4 slots, etc. This exponential lockout makes it increasingly expensive for validators to change their vote, providing economic finality.
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A deterministic mapping of slots to validators for an entire epoch, computed from stake weights. Validators with more stake are assigned proportionally more leader slots. The schedule is derived using a seed from the previous epoch's randomness, so all validators independently compute the same schedule without coordination.
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.
Transaction Processing Unit—the pipeline within a leader validator that ingests, verifies, and executes transactions. The TPU has stages: fetch (receive packets via QUIC), sigverify (verify Ed25519 signatures), banking (execute against current bank state), and broadcast (shred and send via Turbine). Non-leader validators forward transactions to the current leader's TPU.
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.
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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.