Why we don’t set the og:image:alt tag

 Users often ask us why we don’t include a og:image:alt tag in the SEO and social tags that we add to pages. Alt attributes are good for accessibility, so sharing them with Facebook must be a good thing, right? Well, it turns out that it’s not that simple! We actually removed support for the og:image:alt tag in 2019, because we think that it can harm accessibility. Read on to find out why.

Challenges with alt attributes

Alternative text is important for accessibility and to help search engines find out what your content is about. Read more about the importance of the image alternative text. You may also want to learn how to optimize your alternative text for better accessibility and SEO.

Contrary to popular understanding, the alternative text should not describe the image. Rather, it should describe the image’s purpose, which varies depending on usage and context.

The World Wide Web Consortium (W3C) distinguish a few different types of image purpose: Informative images, Functional images, Decorative images, etc. They also provide an Alt decision tree for some quick help on deciding which category a particular image fits into. As a good rule of thumb: Images that are purely decorative don’t need an alternative text. Informative and functional images do.

One image, many alternative texts

The root problem with WordPress (and most similar systems) is that it only allows you to set a single default alternative text. Images often need many different alternative texts, depending on their purpose and context. Luckily, it’s possible to micro-manage the alternative text and change it in the post content, as the default one won’t fit all the use cases. Let’s go through a few examples to better understand this limitation.

We upload the following image to the WordPress media library. The image represents some pizza with pepperoni (note: it’s the Italian version of Pizza with pepperoni):

We set the image alternative text to:

Pizza with pepperoni

The alternative text describes the image, right? We’re all set up then! Wait a moment: Would that alternative text be a good one though? In most cases, the answer is: No. We didn’t take into consideration the actual usage of the image and its context.

Decorative purpose

Let’s say we’re going to use our Pizza image in a post where the image doesn’t add any meaningful information or function to the post content. The image is purely decorative. In this case, we should change the default alt attribute in the post content and make it empty:

<img src="image.png" alt="">