The technique of nesting fragment caches to maximize cache hits is known as russian doll caching. By nesting fragment caches, it ensures that caches can be reused even when content changes. When a change occurs to the top-most fragment cache, only that cache must be expired. Every nested cache of the parent can be reused, which provides a significant performance increase. A change to the most nested fragment cache would start a chain reaction to expire all parent caches.