Flash Sites
As web creation programmes become more developed the ability to offer flash sites has become more widely available. The problem with using flash in a website is that it is unreadable by the search engines. Basically flash is like a mini programme the runs on the web. The search engine can recognize it and display it but can't decipher any information from it as to what your site is about.
Search engines don't see what we see only the code that makes up the site. The code is what provides the search engine all the information about the site and good SEO practices tweak the code to give the search engine lots of additional information, such as words and phrases you consider important for people searching the web for the service you provide. The search engine then in turn will rank you higher for particular information you alert it to. Many flash sites often have a normal html site to deal with this problem.
Frames
The use of frames although providing an advantage to certain aspects of web design are also not recommended as search engines still struggle to navigate the frames. If this site was built using frames then the top banner and menu would be in one frame, this body of text in another and the left a third and the footer a forth.
The search engine reads each frame as a separate entity sometimes only crawling the first frame. As these pages as a whole are built to provide the search engine a complete picture of what this site is about, using frame sets would hamper the effectiveness of getting this site ranked top 10 for our key search terms.
In fact everything that is done in frames is possible in css (what we use). Frames are commonly used in templates and do it yourself sites as manipulating design aspects is easier