Blockchain platforms are base protocols that support distributed ledger functionality, smart contracts, and dApps. Examples include Bitcoin (payments), Ethereum (general-purpose smart contracts), Binance Smart Chain, Solana, Avalanche, and Hyperledger Fabric (enterprise). They differ in consensus (Proof of Work, Proof of Stake, DAG), throughput, privacy, and ecosystem. Platforms provide developer tools, SDKs, wallets, and APIs. They may support public, private, or consortium networks and customization layers. Developers choose platforms based on transaction speed, cost, security, programmability, and community. These platforms power applications across finance, supply chain, gaming, healthcare, and more.