Blockchains provide a decentralized and trustless platform for computing by creating a shared global state through a Byzantine Fault Tolerant system of transaction verification. This allows for applications like cryptocurrencies and smart contracts that provide guarantees around atomicity, immutability, and permanent data storage. While early blockchains were limited in their capabilities, newer platforms like Ethereum enable multi-user accounts, object-oriented programming and interoperability to build a more general world computer. Blockchains reduce the need for trust between parties by diffusing it across the network.