Internet browsing is a wonderful thing; your browser requests a page and 'the internet' returns it to you. Lots of computers around the world, co-operating to respond to these requests efficiently enough to be commercially and socially useful.

Much of this efficiency is gained by storing the results of previous requests in caches within your browser, but also in caches in "the internet" between your browser and the server holding the original page being requested.

The bulk of the book covers issues to do with the caches beyond the browser. Why have caches? That is a necessary component of a firewall; company control and filtering; reduce network traffic; to speed up response times. The politics, copyright and legal (from USA point of view) problems are rehearsed.

A considerable part of the book covers the theory of caching - what do you cache in the first place and what do you discard when the cache is full. How do you get people to use your cache - manual configuration of the browser (fine in a company, but hard work); let the browser discover your cache; to hijacking HTTP requests via an interception cache.

Throughout the book the caching request and response headers are explained in considerable detail. The protocols for caching hierarchies are also covered.

Most of these issues have very specific interest for quite a limited range of people. Of more general interest are the discussions for the web site administrator who either wants to make the most of caching (to give a prompt response), or who wants to ensure their pages are not cached (e.g. to get accurate site use statistics). There is also a useful discussion on how to get the best of both worlds.

The book is well written and logically presented. Recommended if you want to make the most of your high-volume web site, or gain an understanding of the bit of "the internet" between the server and the browser.