13.1. Populate the title attribute on each <iframe>
Whenever an <iframe> tag is included in the page, it is also necessary to add a title attribute.
The attribute value must introduce the content of the <iframe> tag clearly and concisely.
For example, in the case of an <iframe> loading a video player on the page:
<iframe src="https://www.youtube.com/embed/y525BrxyvhA" title="YouTube video: Introducing digital accessibility"> […] </iframe>