Cache hits and misses
Once an object with a particular cache-id is in the cache, a subsequent request for an object with the same cache-id is served from the cache (a cache "hit"). If the object is not in the cache, then the object will need to be created, and served back to the client, as well as stored in the cache to service future requests for the object.
Figure 2-1 A cache "hit" and a cache "miss"