# Endorsement policies¶

Audience: Architects, Application and smart contract developers

Endorsement policies define the smallest set of organizations that are required to endorse a transaction in order for it to be valid. To endorse, an organization’s endorsing peer needs to run the smart contract associated with the transaction and sign its outcome. When the ordering service sends the transaction to the committing peers, they will each individually check whether the endorsements in the transaction fulfill the endorsement policy. If this is not the case, the transaction is invalidated and it will have no effect on world state.

Endorsement policies work at two different granularities: they can be set for an entire namespace, as well as for individual state keys. They are formulated using basic logic expressions such as AND and OR. For example, in PaperNet this could be used as follows: the endorsement policy for a paper that has been sold from MagnetoCorp to DigiBank could be set to AND(MagnetoCorp.peer, DigiBank.peer), requiring any changes to this paper to be endorsed by both MagnetoCorp and DigiBank.