# Key Components

### BNS Registry

The registry is a single contract that provides a mapping from any registered name to the resolver responsible for it, and permits the owner of a name to set the resolver address, and to create subdomains, potentially with different owners to the parent domain.

### Resolvers

Resolvers are responsible for performing resource lookups for a name.

### Registrars

Registrars are responsible for allocating domain names to users of the system, and are the only entities capable of updating the BNS Registry.