CacheObject is the object that is stored in the cache It contains the content, the original URL, and the source URL OriginalUrl is the url of the content that is being cached SourceUrl is the url that requested the content to be cached CacheKey is the key that is used to store the content in the cache Stub is a boolean that indicates if the content is a stub or not Stub indicates that the content is empty and needs to be fetched from the original URL.