Because you have enhanced the meanings of your texts using images and visual design, you have to think about how that will impact readers with visual impairment. Although many people with disabilities use devices or software to assist them, there are still things you can do as a web writer to improve their reading experience. For instance, minimally, any images should have captions or “alt” text (an attribute added to image tags with HTML; WYSIWYGs may prompt you for this) to describe the image for those that cannot see it.
It is particularly critical that any image that does rhetorical work in your web pages have an alt tag. For example, if you use a graphic button as your home link, a blind person will not be able to infer the purpose of the link unless you tag it with something like “alt=”home””.
An automated assessment tool like WAVE: Web Accessibility Evaluation can help HTML coders determine the accessibility of their web pages. Still, WAVE is only going to get you so far if you don’t understand the principles of how to design for accessibility. For an introduction on how to make your website accessible, consult usability.gov’s chapter on accessibility.
Source: Writing Spaces Web Writing Style Guide, available under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) License.