Accessibility rule: Inline frame without a text alternative, explained

High-level description

Inline frames (iframes) are used to embed content into web pages. Technically iframes are elements that load another HTML page to the parent page. Iframes are commonly used for embedding videos, advertisements, and other interactive content, such as social media feeds.
This rule checks that all inline frames have a proper title attribute or aria label.
Example of an inline frame with a descriptive title: 

<iframe title="Map of Siteimprove office" src="siteimproveoffice.html"></iframe>

Who is impacted by this barrier?

While some screen readers consider embedded content in the same way as other page content, other screen readers will announce the inline frame. Without a proper title for the inline frame, users would not know what type of content they are about to access. Is it a map application? Is it a video? Or a social media feed?
Without a meaningful name for the iframe, a screen reader user might just hear “frame” or the file name, instead.

How does the check work in technical terms?

This rule checks that <iframe> elements have an accessible name. Both a label attribute and aria-label are approved by this check. 

You can read more about the SIA-R13 rule in Alfa, Siteimprove’s open-source accessibility conformance testing engine.