I want to know, why IFrames must not be used for a Good Website? Is there any relation of it with SEO? Thanks in advance
Good question. Others might have better answers, but a somewhat educated guess is iframes can cause content to be picked up more than once and can(depending on black hat or white hat) be deceptive. Using a site map has helped me in the past(with google) when using frames that are on my site. I think the fact you can manipulate frames for deception(ie. I am signing up for a puppy grooming newsletter, but really my email is for a porn site opt-in), is a reason why the search engines look at it that way.
I guess you mean to say that it makes the site look like a phishing page? I got some answers but, they were at different perspective.. Anyways, thanks for your time..
Search engines cannot see what is inside the frames. Open up a page with frames and the view the source code. You won't see the content inside the frame. That makes all that content worthless from an seo point of view. You could get the page that actually has the content indexed, but is that the page that you want visitors to see when they find you via a search engine?
iframes do ease the displaying of multiple pages together but should not be used to display a validation form coz it gets to original content on refresh... ... Shud only be used to display static content ..