For those of you who are working to add little bits and pieces of code to your stash of knowledge here's a little tidbit I use on a regular basis.
This is PERFECT for when you have something you change or update on a regular basis, either for yourself or for that client who changes her mind all the time

So - let's say you've got a chunk of your page that you want to 'hide' - you don't want to lose the code because you worked darn hard on it and might need or want it later, but you don't want it showing up on your website - at least for now.
Simply insert the following into your HTML code:
<!-- at the start of whatever it is you want to hide
and
--> at the end of whatever it is you want to hide
So:
<!-- This part of my website code will not show up or take space on the page but will still be visible to me when I go into the backend of my site, keeping it safe and sound for me should I ever want to use it again! -->
Give it a shot