I've always been told that PDFs (Portable Document Format) aren't accessible for people with seeing impairments. Why? It's basically a flattened image, with no text boxes to read. But what I haven't taken the time to do, until now, is learn how to fix that, mostly because I didn't know I could, until a dear friend mentioned that Adobe has indeed made it possible.
I've found some great tutorials online that I will share in lieu of re-explaining everything in my own just-know-enough-to-be-dangerous version.
Making your website accessible is now a part of the ADA thanks to a new amendment back in July. So read up, and fix your websites and posted PDFs as soon as you can to avoid fines.
Adobe has a great 40-minute video (one of the best explained tutorials I've ever watched) on making your InDesign document accessible with walk-throughs for both InDesign and Acrobat to make PDFs fully accessible. Every portion of this video is needed, so don't cheat and cut it short. The last 30 seconds even teach you how to use Acrobat to test how a reader will speak its contents.
For making Microsoft Word, WordPress and other text documents accessible, the National Center on Disability and Access to Education website has an all-in-one link here. http://ncdae.org/tools/factsheets/word.cfm
If you watch the Adobe video first, you'll learn about headings and text styles and why they are important. That information is helpful before you read this page if you are new to tagging, headings, and styles. The video also instructs on adding alternative text to images ("figures") and why that is also important. This page from the NCDAE lists these adaptations but not with in-depth explanations like the video above offers. So whether you use InDesign or not, I suggest watching that video to at least learn the basics on these subjects. This page also mentions that in many cases with MSWord, Mac users aren't able to make some of these changes unless you're proficient in HTML coding, but this article was published in 2006 and I will make the assumption that some changes have been made to this since then.
But in lieu of researching this, since I am not a Mac user, I suggest that those of you who convert to PDFs for simpler emailing and posting, you can instead convert your Word file to a "Read Only" file and skip this inaccessibility all together! I found that that images were easy to tag ("format picture" either under format or right click menu) in Word AND MSOutlook (such as in my signature).
One last point, if you're blogging, writing for Examiner, or making your own website on a user-friendly platform like WordPress, they all ask you for "descriptions" of your images when you upload them, so don't just put in a title, make it descriptive for readers.
Thanks to modern technology this has become a much easier process in just the last two years.