Epoch
An epoch is Solana's staking cycle: a fixed run of 432,000 slots (a slot is the brief window in which one validator can produce a block). An epoch currently lasts about 1–2 days, and it has been getting shorter as Solana speeds up block times. Staking rewards are paid once per epoch.
Why it matters to you
Your stake runs on epoch time. Rewards arrive once per epoch, at the boundary between one epoch and the next, so they won't tick up by the hour. New stake usually starts earning from the next epoch boundary, not the moment you sign. Unstaking follows the same clock: your SOL is usually free to withdraw by the next epoch, sometimes longer when many stakers exit at once.
Epochs are also the unit a validator's record is counted in. One with only a few epochs behind it hasn't had time to show how it behaves, including whether it keeps its fee where it started.
Where you see it on this site
Every Score on this site is recalculated each epoch. A validator with fewer than 5 epochs of history is marked New, and its Score counts as provisional because it can still swing. Our Telegram alerts report your rewards once per epoch.
Questions
Usually within two epochs, so a few days. Your stake typically becomes active at the next epoch boundary, earns for one full epoch, and that epoch's reward is paid at the boundary after it. When many people stake at once, activation can take longer, because the network limits how much stake can switch on per epoch.