The Ethereum Name Service (ENS) is a distributed, open, and extensible naming system based on the Ethereum blockchain. Its purpose is to map human-readable names like 'alice.eth' to machine-readable identifiers such as Ethereum addresses, other cryptocurrency addresses, content hashes, and metadata. ENS also supports 'reverse resolution', enabling Ethereum addresses to be associated with metadata such as canonical names or interface descriptions. ENS has similar objectives to DNS, the Internet's Domain Name Service, but has a significantly different architecture due to the capabilities and constraints provided by the Ethereum blockchain. Like DNS, ENS operates on a system of dot-separated hierarchical names called domains, with the owner of a domain having full control over subdomains.