Social Media and Accessibility
Though social media is heavily reliant on not-so-accessibility-friendly images and video, that doesn't mean it can't be made more accessible. Much social media content is heavy on accessibility traps such as emoji, flattened text (graphic objects that are unreadable by screen readers), and hashtags. Like any other medium, social media posts need to have alternative avenues to the information they contain.
Here is an example:
The text on this image, as far as a screen reader is concerned, isn't text at all. The image is wholly graphic, and pixels can't be translated into words. Since this has both a caption and an image, making it accessible requires a translation of both. Alt text would be something like, "Line drawing of horse, divided in two. Left side realistically drawn, captioned, 'When you use digital resources.' Right side drawn crudely, captioned, 'When you don't use digital resources.'"
It's common for memes to have audio content that differs from their text content -- for instance, a content creator might lip-sync a song or viral audio, but caption the post with different text. To capture the intended doublespeak, you might caption the audio, being careful to make the audio captions distinguishable from the post's text (and to make sure they don't overlap visually).
Adding Alt Text and Image Description to Social Media
Image description and alt text sound like they're the same thing, but they aren't, and especially in social media, you should strive to have both.
Alt text is a short description of the image, embedded in the code that displays the image and not necessarily available to anyone who is not using a screen reader. Image description is a longer and richer description of the image. It appears in the caption of the text and is readable by all viewers. For example, an image description of the horse drawing shown above might read, "A drawing of a horse, divided in two. The left side is realistically drawn with shading and detail; the text on that side reads, 'When you use digital resources.' The right side is a crude line drawing; the text on that side reads, 'When you don't use digital resources.'"
There is a good discussion, with examples, of the difference between image description and alt text in HootSuite's accessibility information.
Instagram: Apparently Instagram generates alt text for every image you upload, though there's no way to check what it comes up with (unless you have a screen reader). The platform offers a way to add your own alt text when you upload your post, though it's easy to miss. Image descriptions can be added at the bottom of the caption; we also enclose them in brackets to distinguish them from caption text.
To add alt text as you upload your post, go to the third screen of the process (after adding the image and choosing, or refusing, a filter) and look for the Accessibility heading. Open this, and there will be a field to add alt text. You'll find it in the same place if you open a published post to edit.
Instagram's alt text is only accessible via screen reader, so you can't see alt text from anyone but yourself, and you can only see your own alt text if you edit your post.
Twitter/X: It is easier to add alt text on Twitter, though it confusingly calls alt text "image description." There will often be no room in a character-limited tweet to add an image description anyway, so perhaps conflating the two makes sense. It's also possible to see the alt text on any post that has it by clicking the white-on-black ALT text box that appears on the image.
To see these illustrations more clearly, right-click on the image and choose Open in New Tab. The new tab will display the image much bigger.
Resources for Social Media Accessibility
Accessi.org: How to Make Your Social Media More Accessible and Inclusive
Social media accessibility hub Accessible Social: Their social media accessibility checklist is a good resource not just for social media but for all accessibility work.
General Services Administration (administers Section 508): Create Accessible Social Media
Yale University's guide: Usability and Web Accessibility: Social Media