SmartContracts

Here's NickSzabo writing on them back in 2002 : https://web.archive.org/web/20020203022707/http://szabo.best.vwh.net/smart.contracts.2.html

Though today we tend to think of them as small scripts on the BlockChain (such as Ethereum)

Smart contracts read and write to the block-chain.

And can be used to create the equivalent of institutions such as DecentralizedAutonomousOrganizations or solve other CollectiveActionProblems. Eg. a multi-sig wallet that can make payments only when all stakeholders have agreed.

See ProgrammingSmartContracts for languages specialized for this