Providing Alternative Text or Image Descriptions allows people with visual impairments using assistive technology to discern the meaning of images online. Without alt text such people would miss the content of the image.
In Blackboard when adding or editing an image use the Image Description or Alt Text field.
Keep in mind the context of the image and the message the image is conveying. For more information and examples of Alt Text read Web AIM’s Alternative Text article.

The alt text for this image is: Blackboard’s Add Image to content area screen highlighting the Image Description field.

The alt text for this image is: Blackboard’s create image item screen highlighting the Alt Text field
Cover Photo by Sergey Shmidt on Unsplash