Alt text, the description of an image added to the HTML code, plays an important role in both your website’s visibility and its accessibility for users. In this article, we’ll explain why alt text is essential, how to write effective alt text, and how to check whether it has been implemented correctly. We’ll also look at the different types of images and why alt text matters for each one.
What is alt text?
Alt text is a short description of an image on a website. It helps search engines and screen readers understand what is shown in the image.
This text provides context so it can be read aloud when someone with a visual impairment visits your page. That’s why alt text is important not only for improving your page’s visibility in search results but also for making your content accessible to everyone.
Why use alt text?
Alt text is important for both search visibility and accessibility. Google can’t “see” images and relies on alt text to understand what an image shows. This is also an opportunity to include relevant keywords naturally.
However, you don’t write alt text just for Google—you write it primarily for your visitors. For example, people with visual impairments rely on screen readers to understand what’s in an image. SEO is always about creating valuable content for users, not just for search engines.
What makes good alt text?
Good alt text is specific, clearly describes what is visible in the image, and includes one or two relevant keywords. Avoid repeating the surrounding text and keep the description short, ideally under 143 characters, so it remains effective for both accessibility and SEO.
How to add alt text
The process of adding alt text varies depending on your website platform and theme, but a few core principles always apply. Use your main and secondary keywords naturally while describing what appears in the image. Make sure the alt text is clear and relevant.
For example, if you have an image of blue women’s jeans, the alt text could be:
“blue women’s jeans.”
How to check your alt text
You can check your alt text by right-clicking an image on your website and looking for alt= in the HTML. If this field is empty, the alt text is missing.
An easier way to check all your images at once is to use Screaming Frog. This tool provides a complete overview of how many images don’t have alt text yet. Do you have a large website? Keep in mind that the free version is limited to 500 pages.
What types of images are there?
There are two types of images commonly used on landing pages or in blog articles: a header image and a supporting image.
A header image often serves as an atmospheric visual, which is fine. However, because this type of image doesn’t always directly relate to the topic, alt text is often overlooked. Even a header image needs a clear alt text description.
A supporting image is more straightforward. This type of image reinforces your content and adds value. Always choose a relevant image and make sure it has an appropriate alt text. Including main and secondary keywords in the alt text helps improve your page’s visibility.
