Alternative Text

Describe what is important in your images so everyone can understand them.

Impact

Images, infographics, and data visualizations can be powerful tools for learning — especially for visual learners. But what about students who cannot see them?

That is where alternative text (alt text) comes in. Alt text is a short description of an image that can be read aloud by screen readers or displayed on Braille devices. It helps students with visual disabilities understand what the image is showing — even if they cannot see it.

But alt text is not just for people with disabilities. It is also helpful when a student:

has a slow internet connection and images will not load
wants to hear the description instead of see it
needs additional guidance breaking down complex visual information

It certain situations, it can have additional benefits such as improving search engine results.

By adding alt text, you are making sure that everyone can access the same information, no matter how they are learning. It is a small step that makes a big impact.

How to

Alternative text is like explaining to a live class what you are writing or pointing to on a whiteboard or screen. You provide only the important points or takeaways, so do the same when describing the image.

Decision Tree

To know how to best provide an alternative for an image, let us go through the decision tree:

What is the purpose of the image?

Can the image be deleted without losing information?
Does the image provide additional mood, connection, or understanding?

If it is purely decorative, then select the image in Canvas and check the box for "Decorative Image".

Extending the same decision tree, does the image present additional information beyond the text on screen? If no, then decorative

New information in the image?

Is there text near the image that provides the same information?
This can be in the form of paragraphs, lists, and tables of text – not images of text.

If the information is already nearby, then select the image in Canvas and check the box for "Decorative Image".

Decision tree at type of information. Alt text for action images needs to be the label of the action, simple images needs short descriptions, and complex images needs summaries and equitable descriptions nearby

What type of information is provided?

Action Images (like buttons or icons)
What to do: Use the Alt Text field to restate the action.
Example: If the image says "Submit," your alt text should be: "Submit".
Simple Images (like photos or illustrations)
What to do: Use the Alt Text field to describe the image briefly — aim for 155 characters or less.
Example: "Student smiling while studying at a library table."
Complex Images (like charts, graphs, or infographics)
What to do: Use the Alt Text field to give a short summary, and let users know where to find a longer description nearby (like in the surrounding text or a linked page).
Example: "Bar chart showing enrollment growth from 2020–2024. Full description below."

Best practices

Focus on what matters.
Only describe the parts of the image that are important for understanding the content. Skip decorative details.
Keep it short — or link to more.
If the image is complex, give a brief summary in the alt text and include a longer explanation in the body of the page or link to another page.
Skip phrases like "image of" or "picture of."
Screen readers already know it is an image, so you do not need to say it again.
Do not use the file name.
Names like "IMG_1234.jpg" do not help anyone understand the image.
Avoid repeating what is already on the page.
If the same information is in the body text, there is no need to duplicate it in the alt text.
Use proper spelling and punctuation.
Alt text is real content — treat it like any other writing.
Make each alt text unique.
Even if images look similar, their purpose might be different. Write alt text that fits the context.

Frequently asked questions

Sometimes an image is too complex to describe in just a few words — and that is okay! You can give students a full explanation by linking to a separate page with all the details.

Here is how to do it:

Create a new page in your Canvas course where you can describe the image using paragraphs, lists, or tables — whatever works best as long as it is text.
Place a link on or near the image that takes students to that page.
Use the alt text to guide students by saying something like:
"Chart showing graduation rates by department. Full description available in linked page."

This way, students using screen readers or Braille displays know exactly where to go for more information — and everyone else can benefit too.

When using images in exam questions, it is important to make them accessible — but also fair. You do not want the alt text to give away the answer. Instead, think of it as a way to guide students to the same clues they would get from seeing the image.

Here is how to do it:

Focus on what you want students to notice.
Describe the key elements or features they should consider — not the conclusion they should reach.
Avoid giving away the answer.
Do not explain what the image means or what the correct choice is. Just describe what is there.
Use red herrings wisely.
If the image includes extra details meant to test critical thinking, include those in the alt text, too. This keeps the challenge fair for all students.
Example:
If the image shows a science experiment setup, your alt text might say:
"Diagram of a beaker with a liquid, a thermometer, and a heat source underneath. A stopwatch is shown nearby."
(This tells the student what is in the image, but not what is happening or what the answer is.)

Additional guidance

You can learn more about providing good alternative text to an image through these accessibility guides: