Alt Text

Alt text stands for alternative text.  It is a text description of an image which is read aloud by screen reading software but not seen on the computer screen.

demonstrating the tool tip for a photograph
Sometimes, people get alt text confused with tooltips or titles – the little pop-ups that are visible when the mouse hovers over an image. The tooltip or title attribute is not usually read by a screen reader.  It cannot be enlarged for low vision users, and it doesn't display in all browsers. It is best not to put important information in the tooltip/title attribute.

Alt text should be added to every image. 
  • If an image adds any new information to the text content, that information should be included in the alt text.
  • If an image does not add any new information to the text content, a short label all that is necessary.
  • If an image is purely decorative, the null alt text is used - double quotation marks with no space in between.  ""

Helpful Alt Text

The first step when determining appropriate alternative text for an image is to decide if the image presents content.  Determining if the image presents content and what that content is can be much more difficult. If the content that the image conveys is presented within text in the surrounding context of the image, then the null alt text may suffice.

The alt text attribute should typically:1

  • Be accurate and equivalent in presenting the same content and function of the image.
  • Be succinct. This means the correct content (if there is content) of the image should be presented as succinctly as is appropriate. Typically no more than a few words are necessary, though rarely a short sentence or two may be appropriate.
  • NOT be redundant or provide the same information as text within the context of the image.
  • NOT use the phrases "image of ..." or "graphic of ..." to describe the image.
    • It usually apparent to the user that it is an image.
    • And if the image is conveying content, it is typically not necessary that the user know that it is an image that is conveying the content, as opposed to text.
    • If the fact that an image is a photograph or illustration, etc. is important content, it may be useful to include this in alternative text.

Examples of Alt Text

Let's look at a couple of examples used in a Freshman Composition course.

Example 1

 Organizing the Essay: Use the Thesis Statement!

Once you have your thesis, many people find it is easier to plan and write the body paragraphs first. Then write the conclusion, and write the introduction last.
example of an image that is a visual representation of the surrounding text


Look at the context of the image. 
  • Does it provide additional information that is not in the surrounding text? 
  • If the image was missing, would a person who is sighted lose any needed information? 
No, the sighted person would not lose any information if the image were removed. In this case, the image is merely a visual representation of the surrounding text. The null alt text would be sufficient.

Example 2

Professor Brown welcoming the class
 Instructor's Overview of the Course

This is the "first day of class lecture"! This is where I get to tell you what I think is important for you to know. I hope you are as excited about the class as I am!
 
Watch the overview video.


Look at the context of the image.
  • Does it provide additional information that is not in the surrounding text? 
  • If the image was missing, would a person who is sighted lose any needed information?   
The sighted person may lose some information if the image were removed. A smiling, friendly image of the teacher may convey a comforting feeling or set a welcoming tone for some students.  This is an example of an image that while not vital to the needed content, does provide additional information to a person who is sighted.  Minimal alt text, like "Prof Brown welcoming the class," would be sufficient. 

Example 3

Evaluating Internet Sources

Some Internet sources publish inaccurate information.  Even though they might be as foolish as a site called www.believe-it.com that publishes images of flying saucers, there are people that believe because the information was on the web.
When you use facts and opinions from sources, you are saying to readers that the facts are accurate and the ideas credible. If you do not evaluate your sources before using them, you risk loosing your credibility (ethos) as a writer. (Gooch and Seyler 203)


"Evaluating Web Sites." University of Texas. 30 April, 2012. Web. <http://www.gslis.utexas.edu/~vlibrary/_assets/ graphics/evaluate.gif>.
Gooch, John and Dorothy Seyler. Argument!, 2e. New York: The McGraw-Hill Companies, Inc., 2013. Print.



Look at the context of the image.
  • Does it provide additional information that is not in the surrounding text? 
  • If the image was missing, would a person who is sighted lose any needed information? 
Yes, the sighted person would lose some information if the image were removed. Even though the image is a cartoon, it conveys the message that there are websites that publish things that are not true. 

This image would need alt text that expresses the meaning as succinctly as possible.  (This is where it gets hard…)  Perhaps something like, "Some Internet sources publish inaccurate information.  Even though they might be as foolish as a site called www.believe-it.com that publishes images of flying saucers, there are people that believe because the information was on the web."

In many cases you can ask the question "If I could not use this image, what would I put in its place?" to determine appropriate alternative text.2

Advanced Images

When an equivalent alternative for a complex image, such as a chart, graph, or map cannot be limited to a succinct alt attribute AND is not presented within the context of the page (such as in an adjacent data table), then the alternative should be provided elsewhere. This is typically done by linking to a separate web page that provides the longer description. The link can be adjacent to the image or the image itself could be linked to the long description page. The alternative text for the image should still describe the general content of the image.3

Learn how to add alt text to images in Word documents.


1"Alternative Text." Web AIM: web accessibility in mind. WebAIM. 29 Aug 2013 Web. 12 Nov 2014. <http://webaim.org/techniques/alttext/>.
2---.
3---.