Quick Links
Have you noticed prompts to write image "alt" text (sometimes stylized as ALT text) when creating blog posts or sharing photos on social media? Here's why this part of the HTML standard is important and how you can write it well.
Why Is ALT Text Important?
Alt attributes exist as a backup form of content; when the main type of content cannot be rendered, its alternate or "alt" attribute is rendered instead. In the case of alt text, if the image cannot be rendered for some reason, you'll get the alt text description instead.
This allows someone, for example, to copy an image "as text." Or if you save a website without any images, the alt text remains, telling you what the images were meant to show.
Alt text is also a crucial component of web accessibility. Visitors have low vision and rely on screen reading software to hear an image's alt text description. If there is no alt text, or if the alt text is poor, that negatively affects the experience of users with visual problems. It can also make navigation difficult for those with limited internet connections relying on text-based browsers.
Alt text is also important in SEO (Search Engine Optimization) since it helps search engines like Google or Bing better index your content. Indexing is what makes content findable with those search engines.
How to Write Good ALT Text
Alt text shouldn't simply be a literal description of what's in your image. You need to consider the context of the image and why it's there in the first place. Consider this image:
If your alt text for this image was, "A large statue of a woman holding up a torch and cradling a book," it would be an accurate description of what's in the image, but it wouldn't be good alt text.
A better description might be, "The Statue of Liberty in New York against a cloudy blue sky." The context of the page matters as well. If the image was part of a news story about immigration, the alt text might be, "The Statue of Liberty in New York, a powerful symbol for prospective immigrants."
Think about the image's purpose, and write your alt text accordingly!
It's important that your primary keyword appears in some of your alt text, but don't put it into every image, especially if the keyword isn't part of a good alt text description
When Not to Use ALT Text
There are two situations where using alt text is something to avoid. The first is for images that are purely decorative. These images aren't interesting to anyone using a screen reader and are irrelevant to your SEO efforts. In fact, describing purely decorative images can muddle search engine indexing and make your article harder to understand for anyone using a screen reader.
As with the general principles of writing good alt text, the decision on whether to write alt text at all rests on what benefits the reader the most. If alt text adds to their understanding and helps retain the value of the original images, you should make an effort to include it.
Adding ALT Text on Social Media
Alt text isn't just something website designers and bloggers must consider. Most of us post images to social media, and most social media platforms offer a way to add alt text to those photos. You may not even be aware of it, but in some cases, alt text is automatically generated using machine vision technology.
The steps for adding or editing alt text on social media change over time as these platforms undergo changes. We've seen many out-of-date instructions for the various social media platforms, so you're the best choice is to check the official documentation for Facebook and Twitter.
Adding alt text only takes a few seconds per image, but it can make all the difference to your content's performance and how accessible the web is to those with visual impairments.