As a domain expert in web technologies, I have been closely observing the evolution of HTML standards and the various elements that have been introduced, modified, or deprecated over the years. When it comes to the question of whether the `iframe` element is deprecated, it's important to clarify a few points regarding HTML specifications and the distinction between different elements that serve similar but distinct purposes.
Firstly, it's crucial to differentiate between the `frame` and `frameset` elements and the `iframe` element. The `frame` and `frameset` elements were indeed part of HTML 4.01, allowing for the creation of multiple, often rectangular, subwindows within a single HTML document. However, these elements have been obsolete in HTML5, meaning they are no longer recommended for use and have been removed from the standard. The primary reason for their obsoletion is that they were not very flexible and did not work well with modern web design practices, including responsive design and accessibility concerns.
On the other hand, the `iframe` element, which stands for "inline frame," is a different beast entirely. Introduced in HTML 4.0 and carried forward into HTML5, the `iframe` allows you to embed another HTML document within the current document. Unlike the `frame` and `frameset` elements, the `iframe` does not divide the browser's window but instead acts as a floating element that can be placed anywhere within the flow of the document. It is widely used for embedding content from another source, such as videos, maps, or even another website, into a webpage.
The `iframe` has several key features that have contributed to its continued relevance and use in modern web development:

1. Sandboxing: It can be configured to act as a sandbox, which helps isolate the content for security purposes.

2. Separate DOM: The embedded document has its own DOM (Document Object Model), which means it does not interfere with the DOM of the parent document.

3. Responsiveness: Modern `iframe` elements can be made responsive, adjusting to the size of the container they are placed in.

4. Content Security Policy (CSP): It supports CSP, which helps prevent cross-site scripting (XSS) and other code injection attacks.

5. Accessibility: The `iframe` element can be made accessible with the appropriate use of attributes like `title` and `aria-label`.
The `iframe` element has not been deprecated and is not going to be, as it serves a different and valuable purpose in web design. It is supported by all major browsers and is an integral part of the HTML5 specification. Moreover, it is often used in conjunction with the `srcdoc` attribute or the `src` attribute to embed HTML content, which can be very useful for a variety of applications, from displaying third-party widgets to sandboxing untrusted HTML code.
In conclusion, the `iframe` element is not deprecated and remains a vital tool in the web developer's arsenal for embedding external content in a secure, manageable, and flexible way. It is distinct from the now-obsolete `frame` and `frameset` elements and should continue to be used where appropriate.
read more >>

First, the frame and frameset elements are not deprecated in HTML5, they're obsolete (i.e., they've been removed entirely). Second, the frame and frameset elements are not the same thing as the iframe element, nor do they give the same output: ... The iframe element, on the other hand, does not replace the body of a page.Apr 15, 2012read more >>