The easiest way to understand the potential need for skip nav link on a site is to hide both images and CSS for the site in question. (You can do this by going into the Web Developer toolbar and replacing images with their
alt text (Images / Replace images with alt attributes) and turning off CSS (CSS / Disable all styles).
Now you see your web page as screen reader software does. Under those conditions, the incarnation of demosthenes.info at the time of writing looks something like the image you see to the left.
The problem is that the screen reader must start at the top of the page, translating the text it encounters into computer-generated speech line by line. That’s not so bad on the blog you’re reading now, with a relatively light horizontal navigation bar. But you can imagine the length of material that would have to be read if the vertical navigation was placed to the left, rather than the right: with CSS turned off it would appear first, meaning that the screen reader would have to read through every piece of sidebar content before getting to the actual content of the page.
To get around this, we introduce a “skip navigation” link as the very first piece of content on the page. That allows people who use screen readers to “skip ahead”, past irrelevant material and get to the meat of the site. The skip navigation works exactly as anchor links do: place an
id on the first piece of “real” content (in my case, the containing
div of the first article), and link to it, just as you would link to an anchor. So in the case of demosthenes.info, the skip nav feature code is simply this:
<a href="#content">Skip navigation</a>
That’s it: so long as the link remains the first piece of body content in the page, screen readers will read that as the first option and allow their users to jump forward to the actual content on the page.
Ironically, the “skip nav” feature doesn’t have to be terribly visible, as it is only screen readers that will encounter it: sighted users don’t need to see it. For that reason, I place it up at the very top left corner of the banner with some CSS, in a non-distracting color.
Modern screen readers don’t need a “skip nav” feature in the site if the pages use ARIA Landmarks extensively.