We discussed the use of iframes in this blog post two years ago, and our conclusion was that you should avoid them.
We revisited the issue recently, and undertook some tests to see if and how we could make iframes SEO-friendly.
The problem with iframes
Pages that have iframe tags display multiple URLs for one single page. You can even have an iframe page in another iframed page. Here is an example:
The html tag indicates the beginning of the code on a page and a conventional page should only have one. In theory, this means that the master page content containing all the iframe tags should be crawled including all associated iframed content. Therefore, link equity can be passed from a master page to an iframed page or vice versa.
In reality, however, there is still a risk that it will confuse search engine robots and result in the page content not being indexed as intended.
Google admit that whilst they try to …