Ethereum Name Services is a naming system based on Ethereum that was started in May 2017. ENS enables users to bind their on-chain wallet addresses, hashes, and machine-readable identifiers with domain names, thus, users can adopt domains like 'alice.eth' as an alternative to represent wallet addresses like '0x787192fc5378cc32aa956ddfdedbf26b24e8d78e40109add0eea2c1a012c3dec'.
ENS differs significantly from DNS (Domain Name Service, centralized domain service provider) in terms of the degree of decentralization. First, ENS is an infrastructure built on-chain and its domains are not manually controlled but operated by smart contracts. Second, ENS is backed by a decentralized autonomous organization (DAO) rather than a centralized authority. Finally, the owner of an ENS domain name has ownership and control over the domain name and can set up subdomains as they want and manage the domains without going through any centralized organization.
Domains system is a critical infrastructure of the blockchain network. Domains can be seen as people's Web3.0 identity. In Web 2.0, websites require users to create a new account to acquire different services or sign on with supported social accounts such as Facebook and Google accounts. In September 2021, a software company, Spruce, launched the "Sign In With Ethereum" project supported by ENS and Ethereum Foundation. It plans to design a standard and secure Web3 sign-in system, and eventually integrate off-chain services and storage.
ENS is a non-profit organization managed by a DAO, and $ENS is its governance token of it. Token holders are eligible for electing root domain managers, setting protocol parameters, and distributing ENS funds. To establish the DAO, ENS announced a token airdrop of 50m $ENS tokens for ENS users and community contributors on November 1, 2021. Half of the tokens would go to users who have registered the ".eth" second-level domain before October 31, 2021, and the rest would go to the 100+ individuals and organizations that have contributed the most over the past four years, as well as Discord users. The remaining 50% of the tokens are reserved for the DAO fund, with a 10% cliff at the time of the DAO launch and the remainder to be unlocked over four years. The exact ENS token distribution is shown in the chart below.
ENS adopts a hierarchical tree structure that can be divided into root domains, top-level domains (TLD), and second-level domains. Each level of domain owner has administrative rights to its sub-domains, for example, the root domain has administrative rights to the top-level domain; the top-level domain has administrative rights to its second-level domain.
As the highest level of the ENS tree, the root domain is responsible for some magnificent events such as introducing new top-level domains, removing the critical vulnerability in a TLD, etc. And it is managed by a multi-signature contract, while the key is held by seven people from different organizations including ENS, Chainlink, Metamask, MyCrypto, Colony, Ethereum Foundation. Additionally, due to the hierarchical structure of ENS, the root has the ultimate control over ENS domains, except for domains that have been sold or rented).
Top-level domains are the tails of a domain, such as '.eth' and '.com'. And ENS does not support all TLDs. At present, the main top-level domains are ".eth" for the Ethereum mainnet and ".test" for the Ropsten testnet. Besides, ENS has integrated the whole DNS namespace, which means that DNS domain owners can import their domains for use on ENS.
Second-level domains, such as "alice.eth", are domain names that users can purchase or lease. Each second-level domain name is an ERC721 NFT and can be traded or transferred on the secondary market. In addition, users can register (lease) domain names with ENS, and the current registration fees are as follows.
The domain owners can create/manage their subdomains, for example, the owner of 'alice.eth' can create 'payment.alice.eth' and 'reserve.alice.eth' for free.
According to its official website, ENS currently supports 60+ wallets (e.g. MetaMask, Coinbase, True Wallet), 400+ applications (e.g. Uniswap, Aave, 1inch), 14 browsers (e.g. Opera, MetaMask Extension, Brave), and tokens of 109 blockchains (2022.11.22).