This link will take you to the web aim wesite, https://webaim.org/articles/pour/. There you can read about accessible design of online content. The main principles of accessible online content are:
This approach looks at the web content from the user perspective. The emphasis is on making web content that is accessible to the user. Making web content that meets the requirements without a sensitivity to the users needs may make navigation and understanding of the content even worse. For example, adding alt text to all images, charts, and graphs is an accessibility requirement. If too general or non-specific alt text is entered it may confuse the reader. Entering alt text of “4 rose” would not provide enough information for a student in a course about the different types of roses. Hopefully this information when assist instructors in creating accessible and meaningful courses for all their students.