What is image alt text?

Alt text is HTML code that is used to describe an image for visually impaired users that rely on screen-readers.

What Is Image Alt Text?

Alt text is written text that appears in place of an image on a web page. This happens when an image fails to load, or when someone uses on-screen reading tools. 

Many companies are learning the value of search engine optimization (SEO) and creating digital marketing content for their business. Keywords, search engine results page (SERP), and cost-per-click (CPC) are all common vocabulary. However, there is another key element of optimization that many people overlook — image alt text. 

Alt Text vs. Alt Attribute vs. Alt Tag

Oftentimes, “alt text,” “alt attribute,” and “alt tag” are used interchangeably. Here is an example of how the code would appear on the page:

<img src="examplepicture.jpg" alt="description of example picture">

The “alt” portion is the attribute of the HTML coding, while the description in quotations is called the alt text. The alt attribute is defined by whatever the text says. An alt tag is a colloquialism people use to refer to the alt attributes and text.  

All three terms are used to describe the same idea — it’s the HTML code that describes a picture.

Why Is Alt Text Important?

Content is generally accompanied by images to create context and make it more user-friendly. Blogging, for example, relies heavily on images to help guide the reader through the post. When these images are optimized, it can help searchers find web pages easier and creates a better user experience. 

Alt text is also important because search engine spiders and crawlers are mainly text-based. They rely on keywords and descriptions to rank websites. Unfortunately, they do not understand images like a human does. Alt text helps search engines understand an image, which helps with the contextual association — and, in turn, the overall ranking of a site. 

Not only does alt text help with SEO, it keeps websites compliant with standards set forth and established via the Americans with Disabilities Act (ADA). The Web Content Accessibility Guidelines (WCAG)  provides the standards for website accessibility and states that text alternative, or alt text, must be provided for all non-text content.

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How To Write Alt Text Correctly

Once learned, writing alt text is a straightforward practice. Here are some tips to writing optimized alt text: 

  • Be specific: Since alt text is supposed to help visually impaired users, the text should be able to explain exactly what’s going on in the image. 
  • Keep it short: Screen-reading tools stop reading at approximately 125 characters. 
  • Use keywords: As stated above, image optimization can help with SEO, though keyword stuffing is still to be avoided.
  • Avoid using “picture of” or “image of”: Alt text already refers to a picture, so using those terms is redundant. 

Alt Text Examples

A woman walks on a trail next to her young son who is riding a bike


Bad alt text: A woman and son in a park

Good alt text: A woman walks on a trail next to her young son who is riding a bike

Five ducklings swimming in a diamond formation


Bad alt text: Cute ducklings

Good alt text: Five ducklings swimming in a diamond formation

Three architects going over construction plans in their office


Bad alt text: A business meeting

Good alt text: Three architects going over construction plans in their office

Using alt text will not only create a better user experience, it will also help a website’s SEO strategy. It is often overlooked, but luckily it is a simple practice to learn.