I think this description is misleading (though I see that unfortunately similar wording is used at https://docs.djangoproject.com/en/1.5/ref/contrib/staticfiles/#django.contrib.staticfiles.storage.CachedStaticFilesStorage). `CachedStaticFilesStorage` doesn't really cache anything itself in any usual sense of the term; what it does is append a content-dependent tag to the filename so that you can safely set far-futures expires (i.e. allow clients to cache the files long-term) with confidence that when the file contents change, the filename will change, thus automatically expiring the cache.

For brief wording here, I'd suggest something like "CachedStaticFilesStorage appends a content-dependent tag to the filenames of static assets to make it safe for browsers to cache them long-term without missing future changes."