ARIA is a set of special accessibility attributes which can be added to any markup, but is especially suited to HTML. The
role attribute defines what the general type of object is (such as an article, alert, or slider). Additional ARIA attributes provide other useful properties, such as a description for a form or the current value of a progressbar.
ARIA is implemented in most popular browsers and screen readers. However, implementations vary and older technologies don't support it well (if at all). Use either "safe" ARIA that degrades gracefully, or ask users to upgrade to newer technology.
Simple ARIA Enhancements
ARIA for Scripted Widgets
ARIA information on blogs tends to get out of date quickly. Still, there is some great info out there from other developers making ARIA work today.