This paper introduces Avalanche, a new blockchain platform aiming for high performance, scalability, customizability, and security for building application-specific blockchains, decentralized applications, and smart assets. It details Avalanche's unique architecture, emphasizing its novel Snow consensus engine* which combines the strengths of classical and Nakamoto consensus for low latency, high throughput, and strong security without relying on proof-of-work. The paper also outlines Avalanche's key features, including subnets for customizable blockchains, a virtual machine model for execution environments, a proof-of-stake based Sybil control mechanism using its native token $AVAX, and a governance system for dynamic parameter adjustments. Furthermore, it touches upon optimizations like pruning and client types, considerations for post-quantum cryptography, and its approach to ensuring inclusion and equal participation.