Alt text, also known as alternative text or, more commonly and incorrectly as “alt tags,” is part of HTML code used to describe the appearance and function of an image on a webpage.

Alt text was created to make websites more accessible for visually impaired users. Screen readers can audibly read an alt attribute, so visually impaired website visitors get a better idea of what’s on your webpage, including images. However, there are other uses for alt text, such as the fact that it can be shown in place of an image if an image file cannot load. Alt text can also give search engine crawlers a written description of what images are, allowing them to index an image.

Why is alt text important?

Alt text is important not only for accessibility, but for SEO. Search engine crawlers read the alt text you write, which further allows the search engine to understand what your website is about. This is why it is critical to provide descriptive, contextual alt text. In addition, search is rapidly becoming visual. You need look no further than Google Search, and the “Image” section of it, to see that you can now search for images as well as websites. These images are ranked using alt text.

In short, alt text gives you increased opportunities to include your target keyword on your webpage. With on-page keyword usage still important as a search engine ranking factor, it is definitely in your best interest to create alt text that both describes the image and, when possible, includes the keyword or keyword phrase that you’re targeting.

How do I write great alt text?

Alt text at its best should be descriptive, accurate and fit within the overall context of the page on which it lives. For example, take the image below:

While an okay alternative text description might be something like, “flowers,” we can really expand upon that, noting all the various attributes of this image. “White and pink flowers growing in a field against a pure blue sky” really provides more information about the image. Keep your text short- the most popular screen readers cut off alt text at around 125 characters, so it’s advisable to keep it to that character count or less. However, search engines don’t have a character limit to what they’ll crawl.

There are many factors in ranking on a search engine, and alt text is one of the factors that is within your control. Using them to your advantage should be a no-brainer in your overall SEO strategy.