Why developers hate iframes? [duplicate]

Possible Duplicate:
Are iframes considered 'bad practice'?

While working with web developers, I always hear from them that using iframes is something we must avoid as we can, and some say it's something bad, annoying and makes a lot of problems.

Also when i told my previous boss "not a developer" one day that i will use iframe, he looked at me as a bad developer :)

What i want to know, does iframes have a very bad history with web development?

Is it a disaster?

In some cases I see that it's a must to use iframes, is saying that means I am a bad developer?

Or all of that because of it's hard to deal with because of some security issues we must take care about while developing?

Please list your points if you hate it too or correct me if I am thinking the wrong way.

Iframes can have similar issues as frames and inconsiderate use of XMLHttpRequest: They break the one-document-per-URL paradigm, which is essential for the proper functioning of the web (think bookmarks, deep-links, search engines, ...).

If you're creating a web application, use whatever technique you want to (including frames, flash, applets, $whatever). If you're creating an actual, informational web page, stick to frameless HTML, CSS and unobstrusive JavaScripts and keep in mind that the page should still be usable with scripting disabled.

As Nosredna said, it's probably because people confuse them with frames, and there are actually a lot of valid arguments against frames. Some of them aren't applicable to iframes, but then again some of them are.

The most striking such issue is probably that of deep linking: It's true that iframes suffer from this to a lesser extent than frames, but if you allow your users to navigate between different pages in the iframe, it will be a problem. There's also a couple of usability problems that you'll have to watch out for. The most common examble is that of double scrollbars, which I personally find incredibly annoying.

I tend to avoid iframes, mostly because I find it to be an unelegant solution. I've found that when I actually sit down and think about it, there's almost always a better solution. Despite that I also believe that there is a place for them. It's the goto of the web world: Just because it has a history of being misused, it has become consensus that it shouldn't ever be used. That really isn't the case here, but I do believe that you should think twice before using iframes.

I wanted to add that most of the time, iframes don't help SEO of a page either. Googlebot doesn't put the content of an iframe on the page.

There is one situation where iframes are (almost) required: when the contents of the iframe is in a different domain, and you have to perform authentication or check cookies that are bound to that domain. It actually prevents security problems instead of creating them.

For example, if you're writing a kind of plugin that can be used on any website, but the plugin has to authenticate on another domain, you could create a seamless iframe that runs and authenticates on the external domain.

I think people confuse iframes with HTML frames, and frames are pretty universally despised.

People use iframes all the time without even realizing it. If I recall correctly, TinyMCE uses iFrames.