Do applets Download every time you visit the page?

Hi friends..
I have a good experience in Java App programming,but nothing about developping Applets!!!
I'm going mke decision about using Applets in our new J2EE project.
Can anyone please answer my question? ( I know that it may seem FUNNY!! but I coulden't find the answer!!)
Let's say I have an applet with the size of 1MB "MyApplet.class" size,when someone loads the page, contains it for the first time it's clear that the .class file must loadup, but what about the secound time?
It loads up again?? Is there any way to prevent this ( I mean from reloading the applet... for example like FLASH files??)
And if it's possible, how can I tell the browser that a new version of the Applet file is on the server?
( I have read the Tutorial at the Sun but couldn't find a help ! )
Can anyone please recommand a good book on (Just Applets)?
Thank you so much

Applets -- the JAR files or .class files -- are cached by the browser just like any other resource. You can control this just as you'd control caching of any other file ("Expires" and "Pragma: No-cache" headers, etc.)

Dear Ernest
Thank you for your response

But how can I tell the browser that the .class files are updated?
( I don't know when they may update! So how can I set the "expires" ?)
And it's very kind of you if you write me an Example? :roll:
[[And your explanations led me to the correct way to find the answer!!
Thank you ]]

Most browsers automatically ask the server if it has a file that's newer than a cached file using a HEAD query; if the server's file is newer, then the new version is downloaded, and you don't have to do anything special. This is going to be fine for 99% of cases. So probably you don't have to do anything at all.

Thank you SO MUCH!