Some web accessibility issues are the result of negligence — others are the result of good intentions.
Many web authors mistakenly believe that alternative text (also called alt text or alt tags) should be applied to every single image on a website. That’s not the case; some images are decorative, and they don’t need alt text. That’s addressed in the very first requirement of the Web Content Accessibility Guidelines (WCAG), the international standards for digital accessibility.
When an image is decorative, it still needs an empty (or null) alt text tag. That instructs screen readers and other assistive technologies to ignore the image (or announce it as decorative, depending on the user’s verbosity settings).
Here’s what null alt text looks like:
<image src=”apple.jpg" alt=””>
Note that the alt text attribute is still there — there’s just nothing in it. This tells assistive software that the image can be safely ignored without depriving the user of anything important.
If an image is decorative, why can't I write "decorative" in the alt text?
Because if an image is truly decorative, the user won’t want to hear about it. They’d rather just ignore it entirely.
Unnecessary noise is a major issue for screen reader users. If their software announces every single element on the page — including things like dividers and borders — they may have trouble staying focused. They might get confused, and they’ll almost certainly feel frustrated.
Related: Perform an Alt Text Audit to Improve Accessibility (and SEO)
How do I know whether an image is truly decorative?
Determining whether an image is decorative requires some judgment, but as a quick rule of thumb, you can try this exercise: Imagine that you’re describing your website to a friend over the phone. Would you explain the contents of the image to your friend, or would you skip it?
You can also ask a few other quick questions about the image:
- Is it part of the page’s visual styling? If so, it’s probably decorative.
- Is it already identified and described by nearby text (such as captions)? If so, additional alt text is unnecessary.
- Does the image communicate anything important to the user? If not, it’s probably decorative.
If you’re still unsure, think about it from a screen reader user’s perspective. Try to determine how alt text (or null alt text) would affect their actual on-page experience.
Related: 8 Common Image Alt Text Mistakes to Stop Making
Can I just leave out the alt attribute entirely?
That’s a logical idea, but no — some screen readers will announce that the alt attribute is missing. Others might use the image’s filename as a stand-in for the missing alt text.
In either case, the user might think that they’re missing important content, which can be confusing. Worse yet, they might think that you don’t care about digital accessibility (which certainly isn’t the case, since you’re reading this article!).
Related: Can You Check Web Accessibility By Downloading a Screen Reader?
Avoid other common mistakes with null image alt attributes
We’ve written extensively about the best practices for writing alt text, and if you’re new to digital accessibility, we recommend reading this guide: 5 Steps for Writing Alt Text for Accessibility.
Some other quick tips to keep in mind:
- If possible, use CSS background images rather than serving images via the <img> element. This removes the need for alt text and provides a more consistent experience across various screen readers. Learn how CSS benefits accessibility.
- If an image is a hyperlink, the alt text should describe the destination of the link. If it’s redundant with a text hyperlink, use null alt text to avoid creating an empty hyperlink.
- When writing any alt text, don’t write too much. Briefly describe the image in simple, objective terms; avoid using words like “image of" or “picture of.”
- When writing alt text for logos, include the company’s name. Please, don’t use “company logo" as the alt text — it’s an extremely common alt text mistake, but that doesn’t make it less frustrating for users.
Whether you're brand new to accessibility or you’re looking for answers to a specific question, we’re here to help. Send us a message to learn how the Bureau of Internet Accessibility can help your organization earn and maintain digital compliance.
