Slot

Instead of competing to find blocks like proof-of-work miners, proof-of-stake validators take turns. Time is divided into slots, and for each slot the protocol pseudo-randomly selects one validator to propose a block, while committees of other validators attest to what they see. On Ethereum, 32 slots make one epoch.

Slots give a network a predictable rhythm. Ethereum produces at most one block every 12 seconds, and Solana's slots are about 400 milliseconds. Builders, relays and MEV searchers plan their strategies around slot timing, and explorers report both the slot number and the block number for each block.

A slot can be empty: if the selected proposer is offline or its block arrives too late, no block is produced and the chain simply moves on to the next slot. Missed slots cost the validator rewards, and a high rate of them signals client bugs or network stress. Slot and block numbers therefore drift apart over time.