Snapshot

A snapshot freezes a blockchain's data at one exact block instead of a clock time, turning a constantly changing ledger into a fixed, verifiable record. Because every full node holds an identical copy of the chain, anyone can independently confirm which addresses held which balances at that precise block, giving a project a tamper-proof list to reward or authorize without asking users to submit anything.

Block height is used rather than a wall-clock timestamp because block production intervals fluctuate slightly, while a block number is permanent, sequential, and identical across every node. Once the target block has passed, moving, selling, or staking the tokens afterward has no effect on eligibility, since only the state that existed at that frozen moment counts. This is what stops someone from buying tokens moments before a vote closes just to swing the result, then selling them straight after.

Snapshots are used for several purposes:

• Determining who qualifies for an airdrop, based on a minimum token balance or protocol usage before the cutoff block
• Recording governance voting power, most visibly on the off-chain platform Snapshot, which lets holders cast gasless votes weighted by their balance at a referenced Ethereum block
• Splitting a chain's history during a hard fork, so holders of the original coin automatically receive a matching balance of the new asset

A common pitfall involves exchange and custodial balances: tokens held on a centralized platform at snapshot time are usually credited to the exchange's own wallet, not the individual customer, so whether a user actually receives the reward depends on that exchange's separate distribution policy rather than the blockchain itself.