All terms
Permission you grant a contract to spend your tokens.
Before a DEX can swap your tokens it needs permission to move them. Many apps request an unlimited approval so you never have to approve again, which is convenient and dangerous.
That permission persists until you revoke it. If the contract is later exploited, the attacker can drain every wallet that still has an open approval.
Review and revoke old approvals every few months at revoke.cash. It costs a little gas and prevents a whole category of loss.
That approvals expire when you finish using an app. Most are unlimited and permanent until you revoke them, which is why wallets drained months after the fact usually trace back to a permission granted and forgotten. Review them the way you would review a standing bank mandate.
Common questions
Why does every swap ask for an approval?
Should I approve unlimited spending?
Where this comes up on the site
The guides that actually use this word, rather than a list of everything we have written.
Where to go next
More security terms
Want this explained out loud?
Some of these land faster in conversation than in writing. Sessions are one to one and you can ask anything, including the things that feel too obvious to ask.