What is a token approval?

A token approval authorizes a specific address to use tokens on their owner's behalf. The authorized address is the spender; the amount it may use is the allowance. For ERC-20 tokens on EVM networks, the token contract stores that permission.

How does the spending limit work?

Example

Suppose you hold 100 sample tokens and grant a swap contract an allowance of 25. Granting permission does not immediately send 25 tokens; it sets a limit the contract can use. In a standard flow, spending reduces the remaining allowance. A new approval can replace the existing limit.

An unlimited approval sets a very high spending limit. More of the same token arriving later may also be exposed while the permission remains active. Permission relates to a particular network, token, owner and spender; approving one token does not automatically authorize access to every asset. The ERC-20 standard defines approve and allowance separately.

How is approval different from connecting a wallet?

Connecting a wallet to an application does not itself grant token spending permission. Disconnecting does not remove permission already recorded onchain. A harmful approval can cause a loss even if the private key was never shared.

Standard ERC-20 allowances have no built-in expiry; other permission systems, such as Permit2, can include time limits. NFT operator permissions differ from ERC-20 amount limits too. Identify the permission type before treating every approval as equivalent.

The token approval review and revocation guide covers locating and removing an existing allowance; disconnecting an app does not revoke an onchain approval.