The Name Wrapper is the ENSv1 contract that wraps an ENS name into an ERC-1155 NFT and adds fuses: permanent permission locks. ENSv2 supersedes it. Roles cover the same ground and can be revoked, so there's no reason to wrap a name today.
Important: don't lock names or burn Fuses. Locked names may have upgrade limits under ENSv2; migration is the recommended path. [More on ENSv2]
Wrapped vs unwrapped
An unwrapped .eth name is an ERC-721 NFT from the BaseRegistrar, and the Manager role sits separately in the Registry. Its subnames are managed in the Registry with no NFT of their own.
A wrapped name is an ERC-1155 NFT from the Name Wrapper, with Owner and Manager collapsed into one account. Subnames of a wrapped name are wrapped and tokenised too. The Name Wrapper can wrap any .eth name or subname, and any DNS name or subname.
Both are ENSv1 constructs. ENSv2 names use neither model. See What are wrapped, unwrapped, and emancipated names?.
What is a fuse?
A fuse is a permanent, one-way restriction on a wrapped name. Burning a fuse turns a permission off for the rest of the current registration: "cannot transfer", "cannot unwrap", "cannot set resolver". The point is the commitment. You burn a fuse to prove onchain that an action will never be taken, and the onchain state is the proof. A reversible flag would be worthless for that, since the owner could un-burn it first. The cost is that there's no undo until the name expires and is registered again.
There are two kinds:
Parent-controlled fuses. Only the parent owner can burn these. They are perks the parent gives the name's owner. Burning
CAN_EXTEND_EXPIRY, for example, lets a subname owner renew their own name.Owner-controlled fuses. Either the owner or the parent owner can burn these. They are permissions being revoked. Burning
CANNOT_TRANSFERmeans the wrapped NFT can't be transferred or sold.
A parent owner can burn fuses at the moment it creates a subname, deciding what perks and guarantees the subname owner gets. See Issue subnames: give away, sell, rent, or ticket for the Fuse combinations each case needs.
How wrapping and unwrapping work
Wrapping a .eth 2LD transfers the Owner (Registrant) of the ERC-721 NFT to the Name Wrapper contract, which then takes over the Manager (Controller) as well. Call wrapETH2LD, or transfer the ERC-721 NFT to the contract directly. Any other ENS name is wrapped by transferring its Manager (Controller) with the wrap method. Either way the contract issues you an ERC-1155 NFT.
You can unwrap at any time with unwrapETH2LD or unwrap, unless the permission to unwrap has been burnt.
Common questions
Should I wrap my name?
No. ENSv2 supersedes the Name Wrapper. If you want fine-grained permissions, migrate the name to ENSv2 and use roles, which cover the same ground without the irreversibility.
Do ENSv2 names have fuses?
No. Fuses belong to the Name Wrapper, which only wraps ENSv1 names. ENSv2 uses roles instead: Renew, Set Resolver, Set Subregistry and Unregister, granted or revoked on a name's Roles tab. A fuse is an irreversible flag; a role is a revocable permission.
What happens to my wrapped name when I migrate to ENSv2?
Fuses convert to roles and the restrictions carry across. See What happens to a wrapped name when it migrates? and Why can't I migrate my wrapped name or subname?.
Is wrapping permanent?
No. A wrapped name can be unwrapped back to the ERC-721 state, unless the "cannot unwrap" fuse has been burnt. If it has, unwrapping is off for the current registration and returns after expiry and re-registration. See Unwrap your name and Name Wrapper: how does expiry work?.
Where do I see a name's fuses?
In the ENS App on Ethereum Mainnet, on the name's Permissions tab. See Change Name Wrapper permissions. In ENS Explorer on ENSv2 Testnet, a Fuses tab appears only on non-ENSv2 names, sitting where the Roles tab would be.