This package provides methods to easier handle caching of HTTP pages. That means that the pages can be cached at the client (user agent or browser) and your application only needs to send "hey client you already have the pages".
Which is done by sending the HTTP-Status "304 Not Modified", so that your application load and the network traffic can be reduced, since you only need to send the complete page once. This is really an advantage e.g. for generated style sheets, or simply pages that do only change rarely.