Ethereum Whitepaper: A Next-Generation Smart Contract Platform

Bitcoin's blockchain is deliberately limited — it's designed almost exclusively to verify and move a currency, with very little room for arbitrary programmable logic. Buterin's whitepaper proposed a blockchain built from the start to run any program (Turing-complete, meaning it can compute anything a general-purpose computer can, given enough resources), where developers write 'smart contracts' — code that executes exactly as written, automatically, with no company or server able to shut it down, alter it, or interfere with it once deployed. This turns a blockchain from just a ledger of currency balances into what's often described as a 'world computer.'