A cryptocurrency blockchain is built as a decentralized, distributed digital ledger that records transactions across a network of computers in a secure, transparent, and immutable way. It begins with the creation of a genesis block, the first block in the chain, followed by subsequent blocks that store batches of verified transactions. Each block contains a cryptographic hash of the previous block, creating a secure link between them. Transactions are validated through consensus mechanisms like Proof of Work or Proof of Stake, ensuring network integrity without the need for a central authority. The blockchain is maintained by nodes (computers) across the network, and once data is recorded, it cannot be altered without altering all subsequent blocks, making the system highly resistant to fraud.
