This document provides guidance on planning, designing, building, deploying, running and tuning highly scalable applications on Windows Azure Cloud Services. It discusses key strategies such as designing applications using scale units consisting of web and worker role instances, saving state externally, employing decoupled asynchronous communications, implementing retry logic, caching data, partitioning workloads and data horizontally and vertically, and monitoring applications internally and externally. The goal is to create scalable applications that can dynamically expand and contract based on demand peaks and distributed, partitionable workloads.