One way sighted people can determine what to put in alt text: Imagine you sent the post or article to a friend, and the image didn't load. What would someone need to know to get the equivalent experience and context? This will help you identify the important details.

When creating PDFs, avoid using "Print to PDF." A screen reader user may still be able to access the text of PDFs created this way, but heading structure, alternative text, and any other tag structure will be lost. Using "Save As" or "Export" can preserve these tags.

When using Microsoft Word or Google Docs, don't just make text bigger and bolder to make it a heading. That will work for sighted users, but screen reader users will miss that and just hear it as normal paragraph text. Use actual heading styles, like level 1 through 6.

When writing alt text for an image of text, it's not enough to just write "screen shot of text from article." Sighted users get to know what is in that screen shot, so why don't blind users deserve the same? The alt text should include all the actual text in the image.

When you make the pitch for accessibility, be prepared for pushback. There are several myths and misconceptions, so it's good to be aware of what they are and how to dispel them.

Accessibility Myths

A small project debunking common accessibility myths.

People who are new to writing alt text sometimes feel they must describe every detail in every visual, including logos. This is unnecessary and will overwhelm screen reader users. For example, it's OK to write "Google logo" rather than describing the logo in exhausting detail.

For beginners, it can be difficult to know what to put in alt text, as well as when alt text is needed and when it isn't. This decision tree from @w3c helps you determine what to do, based on specific situations.

Web Accessibility Initiative (WAI)

An alt Decision Tree

Accessibility resources free online from the international standards organization: W3C Web Accessibility Initiative (WAI).

You don't necessarily need to say "image of" in your alt text for users to know it's an image. Screen readers will announce that it's an image. But it can help readers to specify if it's a hand-drawn image, Polaroid, infographic, screenshot, chart, map, diagram, or so on.

You probably wouldn't publish an article filled with mistakes, so don't do it with transcripts or video captions, either. Auto-transcription services can be a great starting point, but that's what they are: a starting point. They still need editing to be publication ready.