How does the webplayer caching work without Unity Pro

How does the webplayer caching work without Unity Pro.Resources saving in local cache of users' can accelerate them to open it.How to do it .Does Unity Pro necessary ? thank u

There are different things here. There is the browser's built-in cache, which should always work, but you have no control over it. Then there is Unity's caching system, which allows you to cache whole games on the user's hard disk, but this requires a custom license. Starting with the soon-to-be-released Unity 3.2, we will change this a bit, making a small shared cache available to all Unity users, regardless of license.

Unity Pro is not enough. Caching requires that you license the caching explicitely per project from Unity Technologies, you can not use it otherwise.