Ethereum

Ethereum is a decentralized platform to run smart contracts. It is administered by the Ethereum Foundation.

Smart contracts are called Dapps and communicate with each other using the Whisper protocol.

The role of the customer (currently humans) stands to be dominated by machine function as smart contracting systems enable end-to-end payments without requiring a human initiator. What Ethereum will help facilitate is an economy of interconnected devices where machines can transmit money and data in a manner which dwarfs the efficiency of human input. Businesses which overlook this trend, will pay dearly due to new supply channels which disintermediate the old world’s necessary third parties.¹

By default, the Ethereum execution environment is lifeless; nothing happens and the state of every account remains the same. However, any user can trigger an action by sending a transaction from an externally owned account, setting Ethereum's wheels in motion. If the destination of the transaction is another EOA, then the transaction may transfer some ether but otherwise does nothing. However, if the destination is a contract, then the contract in turn activates, and automatically runs its code.²

[1] https://www.diginomics.com/2016/03/07/ethereum-virtual-machine/

[2] https://github.com/ethereum/wiki/wiki/Ethereum-Development-Tutorial