This chapter introduces the foundational mechanics of the Bitcoin blockchain. You will learn how Bitcoin structures data through addresses, transactions, and blocks, and how it ensures integrity using cryptographic hash functions and Merkle trees. We explain how users interact with the network via a peer-to-peer architecture and how mining, Proof of Work, and block rewards secure the system and control coin issuance. The chapter also covers key design upgrades such as Segregated Witness, Taproot, and hierarchical wallets, and explains how forks, mempools, and scripting govern Bitcoin's functionality. By the end, you will understand the core components that make Bitcoin a decentralized, trustless, and resilient financial protocol.