This document provides an introduction and overview of blockchain technology. It begins with key concepts, explaining that blockchain allows parties to reach consensus without trusting each other through decentralization, security, and immutability. It then discusses how blockchain works, including the roles of wallets, miners, and consensus algorithms like proof of work. The document reviews the state of the art, including examples of cryptocurrencies, digital assets, identity solutions, smart contracts, decentralized applications, and challenges to adoption. It positions blockchain as a foundational technology that is just beginning to transform how information and value are transferred.