Every ENS lookup starts with the Registry—a smart contract that tracks who controls each name and where to find its records.

The Registry stores two pieces of information for every ENS name: the Manager (who controls it) and the Resolver (where its records are stored).

As you can see, the Registry can have entries not just for .eth names, but all DNS names (like domain.com or domain.xyz) and subnames too (like sub.name.eth or sub.domain.xyz).

The Manager is the account that controls the name. By interacting with the Registry contract, the Manager can update the Resolver, create or update subnames, or transfer the Manager to a new account.

When making an ENS lookup, the system first retrieves the Resolver address from the Registry.

A Resolver is a smart contract that “resolves” or “points” an ENS name to records. You can store Ethereum addresses, Bitcoin and other cryptocurrency addresses, text records like email or Twitter handles, and more.

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Together, the Registry and the Resolver are the two contracts forming a two-step lookup system. For example, to look up the ETH address for name.eth:

User CodeENS RegistryResolver @ 0x1234...1. Retrieve the Resolver from the Registry for node "name.eth".

Call the Resolver contract to retrieve the ETH address record for node “name.eth”Resolver('foo.eth')0x12342...addr('foo.eth)0x2345...User CodeENS RegistryResolver @ 0x1234...

If no Resolver is set in the Registry for the name, then it does not resolve or point to any records.

A Registrar is a smart contract that controls a top-level name (like 'eth') and lets people register subnames under it (like 'yourname.eth'). Each Registrar sets its own rules for registration—including pricing, character limits, and availability.

The .eth Registrar owns the “eth” node and issues subnames such as “name.eth”. This is also commonly referred to as the “NFT contract” for ENS names, because when a .eth name is registered, the contract will issue an NFT to the Owner.

The Owner holds the NFT and has ultimate control over the .eth name.

Every .eth name has an Expiry or Expiration Date—when it expires, you'll need to renew it to keep control.

When you register a .eth name, the Registrar automatically sets you as the Manager in the Registry. Typically, the Owner and Manager are the same address.

But you can set a different Manager address, or transfer the NFT to someone else later. When the Owner and Manager differ, the Owner can always reclaim Manager rights by overwriting the current Manager in the Registry.

You can register .eth names with 3 or more characters, with pricing based on name length. You can renew your name before it expires to extend your ownership.