How do sites quickly make updates to thousands of pages with user created content without affecting the old content. I know you can do it in php resulting in urls such as .../profile.php?id=000000000&ref=nf such as facebook does. I don't know php but maybe there is a way to get the same effect without affecting the url (witch is my goal). Digg.com is another site that i saw go through an update, updating all old pages as well and there urls don't look like that. At first I thought it was all done through css but I don't think some of that changes they made are possible through pure css. If you can help me in any way learning how to build this capability that would be great. thanks

They use one common external style sheet for all of their web pages. All they have to do is change the style sheet, and the whole look of the site changes.

I agree with midimagic that the proper way is to use a external css file and then import the css. In this way if you change single external css file than the whole look of the site gets changed.

How do they add a new menu item through css?

Have one page with the menu on it, and put links to that page in all the other pages.

Or edit each page separately to add the item.

I'm saying they added new menu items to thousands of pages quickly. The changes were seen on every page. Are you saying the code for the menu was imported from another file? There is no way they edited each page.

In sites I design, I create my menus using javascript. By changing one file, the menu is updated on every page that calls the script.

Cool thanks, thats one way I look into.

Something else I just thought of is there anyway to batch edit html files?

Another possibility is that they edited the files offline, and then uploaded them nearly simultaneously.