You know the basics of HTTP caching. Setting HTTP expiries on a document has no secret for you, you know how to prevent a browser from caching dynamic content and you're pretty happy with If-Modified-Since. In this session, you will discover the actual difference between strong and weak etags, how to invalidate URIs, use reverse-proxies efficiently and how much freedom the client has in overriding defaults and bossing proxies around. And if you are worried of learning all this on your own, fear not, an old friend will be there learning with us.