Sure, here's a response to "what is ethereum?" based on the search results you provided:

Ethereum is a blockchain-based platform that enables developers to build decentralized applications (dapps) and smart contracts. It was created in 2015 by Vitalik Buterin and has since become one of the most popular blockchain platforms in the world[1].

Ethereum has its own cryptocurrency called Ether (ETH), which is used to pay for transaction fees and computational services on the Ethereum network.