Alternative text, often called alt text, is one of the clearest examples of the difference between technical accessibility and meaningful accessibility.
Accessibility tools can often determine whether an image contains alt text. That information is useful because it helps identify images that may need attention. However, those tools cannot reliably determine whether the alt text actually helps a student understand the content being presented.
What is the Purpose of Alt Text?
The purpose of alt text is not simply to announce that an image exists. Its purpose is to communicate the information, meaning, or context that the image provides.
When creating alt text, consider a simple question:
What does a student need to know from this image?
The answer should guide the description.
For example, images that are used solely for aesthetic purposes and do not add any context do not need alt text and can be marked as decorative. However, if the image supports learning, explains a concept, presents data, or provides instructions, the alt text should communicate the information that students need to understand.
To experience how alt text works with screen reader technology, watch our short Alt Text Simulator video.
Alt Text Requires Human Judgment
Like accessibility scores, alt text illustrates the limitations of automated accessibility tools.
An accessibility checker can identify whether alt text has been added. It cannot determine whether the description is useful, accurate, or meaningful.
For example, an image with alt text that says “chart” technically contains alternative text. However, that description does not help a student understand what the chart communicates. A more effective description would explain the trend, comparison, or conclusion that the chart is intended to convey.
The difference isn’t whether alt text exists, but whether it communicates the information successfully.
Complex Images Need More Than Alt Text
Some images contain more information than can reasonably fit into a short description.
Graphs, diagrams, timelines, infographics, and screenshots often require additional explanation. In these situations, provide concise alt text that identifies the image and its purpose, then include a longer explanation nearby in the document or webpage.
This approach ensures students using screen readers have access to the same information as students who can view the image.
Faculty Takeaway
Good alt text focuses on meaning, not appearance. Use accessibility tools to identify missing alt text, but don’t stop there. Review images from the student’s perspective and ask whether the description communicates the information the image is meant to convey.
The goal is not to tell students that an image exists. The goal is to ensure that they understand what the image contributes to the learning experience.
Related Workshops
Accessibility: The Art of Alt Text will be held online on Wednesday, September 30, 2026, from 10 – 11 a.m.
For more information, see upcoming accessibility workshops on the GGC Events calendar.