Search engines have a tough time with frames. Using frames either prevents them from finding pages within a web site, or it causes them to send visitors into a site without the proper frame "context" being established.

If you saw a single page with three frames appear. The content for these frames actually came from three different pages and was blended together according to the instructions of a fourth "master" page, also called the "frameset" page.

In contrast, most search engine spiders will only see the master page. Just like an old browser, they don't understand the instructions on how to produce the frame layout. These are ignored and only information within the noframes tags are read (information which a frames-capable browser will ignore).

There's also another problem. There are no links within the noframes area to pages within the site. That means the search engines won't crawl past our master page. We could have hundreds of information-packed pages inside the site, but this simple mistake essentially makes them invisible to many search engines.