Glossary · Smart Contracts
Validity range.
A slot interval during which a transaction is considered valid. Outside the window, the chain rejects it.
Think of it as
A "best between" date stamped on the transaction. Outside the window, the network throws it out.
In depth
Every Cardano transaction can carry a lower and upper bound on slots, `invalidBefore` and `invalidHereafter`. The transaction can only land in a block whose slot is inside that range. Scripts read these bounds (not the "current" slot, there isn't one inside a script) to enforce time-based rules: vesting windows, auction deadlines, expiry timeouts.
Example
A vesting validator checks that `tx.validityRange.lowerBound >= unlockSlot` to confirm the unlock time has passed before letting the beneficiary claim.