The document discusses best practices for virtualizing Microsoft Exchange Server 2013. It recommends virtualizing Exchange for standardization, optimizations in deployment, management, and monitoring. However, virtualization may increase complexity and impact performance. The Microsoft Exchange team supports virtualization when sized correctly to avoid oversubscription issues. Key best practices include avoiding single points of failure, properly sizing virtual machines for CPU and memory, and using features like storage area networks and database availability groups for high availability rather than host-based clustering or hypervisor snapshots.