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Every Ethereum node runs the EVM in order to maintain consensus across the blockchain. Decentralized consensus gives Ethereum extreme levels of fault tolerance, ensures zero downtime, and makes data stored on the blockchain forever unchangeable and censorship-resistant.
Ether
Ether is the cryptocurrency of the Ethereum Blockchain. It is a necessary element -- a fuel -- for operating the distributed application platform Ethereum. It is a form of payment made by the clients of the platform to the machines executing the requested operations. To put it another way, ether is the incentive ensuring that developers write quality applications (wasteful code costs more), and that the network remains healthy (people are compensated for their contributed resources). For details see https://www.ethereum.org/ether
Wallet
To manage your Ether and Tokens comfortably, you need a special software application called Wallet. The Mist Wallet is an open source application developed by the Ethereum Foundation.
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