Community Submission - Author: John Ma
Traditionally, the term snapshot refers to the ability to record the state of a computer system or storage device at a specific point in time. In cryptocurrencies, a snapshot is often describing the act of recording the state of a blockchain on a particular block height. In this case, the snapshot records the contents of the entire blockchain ledger, which includes all existing addresses and their associated data (transactions, fees, balance, metadata, and so on).
Snapshots are commonly used during airdrops events before each round takes place. During an airdrop, tokens are distributed based on the balance of each blockchain address. In this case, snapshots are taken to record the balance of each token holder, at a specific point in time (i.e., block height). In most cases, users can move their funds after the snapshot is taken, without compromising their eligibility to participate in that round of distribution.
Snapshots are also important during blockchain hard forks, as they mark the block height in which the main chain will be recorded before giving birth to the new chain. For instance, when the Bitcoin Cash hard fork took place (on August 1st, 2017), every blockchain address that had Bitcoins at block 478,558, had the balance copied on the Bitcoin Cash blockchain. The reason for that is because both blockchains share the same historical data prior to the fork. As soon as the split is done, each blockchain network will operate independently.
Another use of snapshots is to record the BNB balance of users that are willing to participate on Initial Exchange Offerings (IEO) that take place on the Binance Launchpad. However, the snapshots follow particular rules, according to the guidelines of each project. In some cases, the snapshots are taken at a random time each day, and the users’ balances are averaged within a predefined period.