The Google 304

Notice the "Mark New Content" button.

To speed up the web Google uses a quick 304 request to find out if your web pages have been modified or not.

Google is actually reading the time stamp of the file as it's stored on the hard drive of the web server. If the time stamp matches the stamp from the last visit Google will jump to the next page without reading.

The problem with this is that sometimes Google misses new content that you enter through a CMS.

You see, the CMS will build your pages on the fly and populate the existing files that's saved on the hard drive. The content changed, but the file date didn't.

For this reason GlitterPaw has the ability to "Mark New Content" which is a quick way to rewrite the file back to disk.