ApprovalForAll

ApprovalForAll refers to a mechanism in ERC-721 and ERC-1155 token standards that allows an owner to authorize or revoke an operator to manage all of their tokens. It is implemented via the setApprovalForAll function and the ApprovalForAll event. The owner calls setApprovalForAll(operator, approved) to grant or revoke operator rights. An operator can transfer, including safeTransferFrom, on behalf of the owner for all tokens owned by that owner, subject to the approved flag. This contrasts with the single-token approval, where a specific tokenId is approved for transfer by a given operator.

Typically used by marketplaces, custodial wallets, or automated systems that need to manage multiple tokens for a user without requiring separate approvals for each token. It enables gas-efficient listings and automated sales, but also increases risk: an approved operator can move or transfer any of the owner's tokens across all contracts that implement the standard, so approvals should be given only to trusted addresses. To revoke, the owner calls setApprovalForAll with approved = false.

Events: ApprovalForAll is emitted when the approval status changes, allowing off-chain trackers to monitor who is allowed to manage tokens of a given owner. The mechanism is widely used in NFT ecosystems to enable bulk management while maintaining on-chain auditability.