They often ask if they should do their site with frames or not. From the standpoint of designing and maintaining a website, HTML frames seem wonderful. But from a customer and marketing standpoint, frames can create serious problems. Frames prevent visitors from bookmarking internal pages. This stops potential customers from coming back to your site and easily returning to what they were looking for.
Frames inhibit search engine effectiveness .
Frames keep directories from linking to interior pages . Frames may not fit your visitor's monitor . Frames often assume an 800x600 pixel configured monitor, and make your site hard to view with a smaller monitor configured to 640x480 pixels. Frames can't be printed correctly with some earlier browsers. There are a few cases where frames are the best solution to a website design problem, but unless you must use them, I recommend that you don't.