No Cache_______________
Sometimes when you make a new layout or change a lot of things around on your site and you go to preview it, you have to either wait awhile or refresh it a few times before your new things show up. If you add this code, then you won't ever have to do that again :)
Place these two codes (keep them together) between the HEAD and /HEAD tags of your page. Remember, they go on your index (or your main) page.