Yeah.. that's what I do when I'm ready to make the changes. But instead of trying out a hundred things when I'm not sure what part of the code controls what.. or if I just want to see how something would looks like.. and then editing a file and uploading it.. I can use Firebug to make the changes in my browser window to see if I like how they look or if I'm editing the right bit. If I don't like it, I refresh my window and try something else out. Better than backing up files.. accidentally overwriting them.. hitting undo a hundred times or restoring a backup when you upload something and don't like it.