Thread:Mathmagician/@comment-4731838-20120831052830/@comment-4674838-20120831055033

maxage and smaxage are basically the number of seconds old the resource can be. So if you load a script or resource with maxage=0, that means 0 seconds, so on every page load it has to get an up-to-date copy and bypass your cache.

On the other hand, if you have maxage=86400, that's exactly 1 day = 24 hours = 3600 minutes = 86400 seconds until the resource has to be refreshed.