The smallest unit of block data propagated through the network via Turbine. Blocks are split into shreds of up to 1,228 bytes each (fitting in a single UDP packet). Shreds are Reed-Solomon erasure coded—typically 32 data shreds produce 32 recovery shreds—so blocks can be reconstructed even if up to half the shreds are lost.
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The smallest unit of block data propagated through the network via Turbine. Blocks are split into shreds of up to 1,228 bytes each (fitting in a single UDP packet). Shreds are Reed-Solomon erasure coded—typically 32 data shreds produce 32 recovery shreds—so blocks can be reconstructed even if up to half the shreds are lost.
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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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Shred (shred) Category: Core Protocol Definition: The smallest unit of block data propagated through the network via Turbine. Blocks are split into shreds of up to 1,228 bytes each (fitting in a single UDP packet). Shreds are Reed-Solomon erasure coded—typically 32 data shreds produce 32 recovery shreds—so blocks can be reconstructed even if up to half the shreds are lost. Related: Block, Turbine, Erasure Coding
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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.
Solana's block propagation protocol inspired by BitTorrent. Instead of the leader sending a full block to every validator, Turbine organizes validators into a layered tree and propagates shreds through successive tiers. Each node forwards shreds to a small fanout set, reducing the leader's bandwidth requirement from O(n) to O(log n).
A Reed-Solomon error-correction scheme applied to shreds during block propagation. The leader encodes each batch of 32 data shreds into 32 additional recovery (parity) shreds. Any 32 of the 64 total shreds are sufficient to reconstruct the original data, providing 50% loss tolerance during Turbine propagation.
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Solana's parallel transaction execution engine. Sealevel can process thousands of transactions simultaneously by analyzing each transaction's declared account inputs—transactions that don't touch the same writable accounts run in parallel across available CPU cores. This account-level parallelism is what enables Solana's high throughput.
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 serialized copy of the full accounts state at a rooted slot, used for fast validator bootstrapping. Full snapshots contain all accounts; incremental snapshots contain only accounts modified since the last full snapshot. New validators download a snapshot instead of replaying the entire ledger history, reducing sync time from days to minutes.
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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.
Solana's block propagation protocol inspired by BitTorrent. Instead of the leader sending a full block to every validator, Turbine organizes validators into a layered tree and propagates shreds through successive tiers. Each node forwards shreds to a small fanout set, reducing the leader's bandwidth requirement from O(n) to O(log n).
A Reed-Solomon error-correction scheme applied to shreds during block propagation. The leader encodes each batch of 32 data shreds into 32 additional recovery (parity) shreds. Any 32 of the 64 total shreds are sufficient to reconstruct the original data, providing 50% loss tolerance during Turbine propagation.
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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.