In 2014, Vitalik Buterin explained decentralized applications (dapps) and Ethereum. He notes that dapps reduce costs, remove points of failure, prevent censorship, promote transparency and trust.
Ethereum borrowed the concept of distributed consensus and cryptographic proof that makes cryptocurrencies such as Bitcoin so effective in trustless payments. Ethereum then extended the use of these technologies to trustless agreements (Smart Contracts). This allows developers to easily build innovative, new products on a collusion-resistant foundation without censorship.
In brief, Ethereum is a platform that makes it possible for any developer to write and distribute next-generation dapps.
Vitalik Buterin is a Russian-Canadian programmer and writer primarily known as a co-founder of Ethereum and as a co-founder of Bitcoin Magazine.