221 Real Estate uses an Etherum private blockchain. Hence, nodes participating in transactions are authenticated and authorized machines within the organizational network. Ethereum is a programmable blockchain – it allows 221 Real Estate to create operations, coded as Smart Contracts, deployed and executed by the Ethereum Virtual Machine (EVM) running inside every node. A blockchain is a distributed computing architecture where every node runs in a peer-to-peer topology, where each node executes and records the same transactions. These transactions are grouped into blocks. Individual user interactions (transactions) with the ledger are append-only, immutable, and secured by strong cryptography.