When it comes to framed sites and the effect that the use of frames by a site has on its search engine ranking, there are two schools of thought. Some people say that framed sites, if done properly, have no problems in getting good rankings in the search engines. Others claim that if search engine optimization is important to you, never use frames.
In my opinion, the truth lies somewhere in between. Yes, the use of frames does throw up a few issues when it comes to getting good rankings in the search engines which don't understand frames. Hence, when you are designing a new site, I would recommend that you avoid using frames, unless you have a specific reason for doing so. However, if you already have a site which uses frames, all is not lost. You can still get good rankings in the search engines even though you have used frames. Furthermore, using frames also has its own advantages when it comes to search engine placement, as we shall later on. This article assumes that you have a working knowledge of frames. For more information on frames, go to http://www.webreference.com/dev/frames/
In case your site uses frames, the key to getting good rankings lies in using the NOFRAMES tag. The NOFRAMES tag is intended to help framed web sites display some content for those people who are using browsers which don't understand frames. The search engines which don't understand frames also look at the NOFRAMES tag. Hence, if you are using frames, you need to add content to the NOFRAMES tag.
What you should do is to add a complete web page within the NOFRAMES tag. Ensure that this page repeats the important keywords for your site a number of times. Also, in order to ensure that the content within the NOFRAMES tag is as prominent as possible to the search engines, you should put the NOFRAMES tag right after the FRAMESET tag. However, don't put the NOFRAMES before the FRAMESET tag. If you do that, Internet Explorer will display your site correctly but Netscape will display the content present in the NOFRAMES tag, rather than the content present within the frames. Furthermore, you should also place a link to the page containing your navigation links in the NOFRAMES tag. This ensures that the search engines are able to spider the internal pages in your site.
One problem that occurs when you use frames is that the search engines may often display one of the internal pages in your site in response to a query. If this internal page does not contain a link to the home page of your site, the user will be unable to navigate through your entire site. The solution, of course, is to add a link to the home page from that internal page. When the visitor clicks on that link, she is brought within the context of the frames.
However, simply adding a link to the home page presents yet another problem. If the visitor had already been viewing that page within the context of the frames and then clicks on the link to the home page, a new set of frames will be created in addition to the frames already being used. In order to solve this problem, you have to use the TARGET = "_top" command in the link.
As I mentioned earlier, there is also an advantage to using frames. Since most Internet users are now using frames enabled browsers, it means that not many people are going to know what's present in your NOFRAMES tag. This allows you the repeat your keywords a few more times in the NOFRAMES than what you could have done if you were writing a page which humans would also see (of course, don't repeat the keywords too many times - that can cause your web site to be penalized for spamming). You can also avoid using tables, graphics etc. which you would otherwise need to use if humans would also view that page. However, it is debatable whether this small advantage is sufficient to justify using frames.