$ETH Ethereum is a peer-to-peer network that maintains a database containing the storage values of all Ethereum accounts and processes state-altering transactions.[59] Approximately every 12 seconds, a batch of new transactions, known as a "block", is processed by the network. Each block contains a cryptographic hash identifying the series of blocks that must precede it if the block is to be considered valid. This series of blocks is known as the blockchain.[60]

Each "node" (network participant) connects with a relatively small subset of the network to offer blocks and unvalidated transactions (i.e. transactions not yet in the blockchain) to its peers for download, and it downloads any of these from its peers that it doesn't already have. Each node usually has a unique set of peers, so that offering an item to its peers results in the propagation of that item throughout the entire network within seconds. A node's collection of unvalidated transactions is known as its "mempool".[61]