This document discusses using Windows Server AppFabric caching to scale data layers. AppFabric caching provides a distributed, in-memory cache that can span machines and processes. It addresses issues like limited cache memory on individual servers. The document outlines how AppFabric caching works, how to install and configure it, and how to access the cache through the API. It also describes features like data distribution, eviction policies, and change notifications that allow the cache to efficiently scale to large workloads and data sets.