In the case of the World Wide Web, authoring means posting stuff to a medium that has shaken the world. Nations fear it so that they try to control it but since they can't survive without it, give in. Enterprise embraces it so as not to be left out of its promise of vast gain. Creators flock to it in order to fling their missives of emotion and thought to one another.
Everyone, everything connected is our cherished dream. How then do we take part? What magic must we weave to have our message emblazoned on this wondrous Web? The answer is that we use something that belongs to a class of tools called "Web Authoring Tools." We can create an image or set of words or music or whatever and through the careful selection of an authoring tool present it to the whole world - all at once - almost without cost!
In an effort to assure that nobody gets left out the Web Access Initiative has published a set of guidelines that attempt to insure that people with less than the latest fancy equipment, less than the usual technical or physical abilities, less than what the big dogs eat, can still take part in this marvel. The purpose of the Authoring Tools Accessibility Guidelines is to help the developers of these tools make their products usable by anyone and that what they put on the Web is accessible to everyone. As Daniel Dardailler says: "A document is accessible if it can be equally understood by its targeted audience regardless of the device used to access it. An accessible document is also defined by conforming to the Web Content Accessibility Guidelines."
Since in many cases the "targeted audience" is all of humankind, the task of the Web Authoring Tool Designer is of paramount importance. The people who do this can form a "choke point" that restricts Web content to some elite fraction or they can open the process so that everyone can: use their tool; access the tools' output.
Although the guidelines are almost opaque to someone not versed in the alphabet soup of languages, protocols, and other arcana, to their intended audience they are fairly straightforward, though subject to endless nit-picking discussions. At bottom they are intended to allow us to publish. Some of the tools take intense study just to learn to use them; others are almost automatic. All of them should be accessible to anyone willing to learn their use, regardless of disability. That is, within the intended group of users for a particular tool, there should be no discrimination due to physical limitations of the user and importantly, the output of the tool should be available for everyone.