Here's a summary of Ethereum (ETH) in 250 characters:

"Ethereum (ETH) is a decentralized blockchain platform launched in 2015 by Vitalik Buterin. It enables creation of smart contracts and decentralized applications (dApps) beyond digital currency. Ether (ETH) is its native cryptocurrency, fueling network operations and app development. Ethereum's smart contracts automate processes, ensuring transparency and security."