What is a "skip navigation" link?
Many web sites have redundant navigation systems across multiple pages. Usually these navigation systems include several links across the top and/or down the left side of the page. For screen reader users and users navigating by keyboard, these links can become burdensome if there is no way to efficiently skip past them. A sighted user can jump visually past these links and begin reading the main content of the page. A "skip navigation" link is a technique for facilitating similarly efficient access for users with certain disabilities. A "skip navigation" link is implemented by placing a named anchor at the point on the page where the main content begins (e.g., <a name="content">). Then, place a same-page link at the beginning of the page that targets this named anchor (e.g., <code><a href="#content">Skip to main content</a></code>).
Accessibility experts such as Jim Thatcher, advise that with the correct usage of headings markup (h1, h2, h3), the need for skip navigation links are eliminated. This is due to the advanced features of screen readers, which allow users to skip past repetitive navigation links with keyboard commands to jump from heading to heading.
For additional information, consult the article Is it ok to make "skip navigation" links invisible? and Does CSS positioning eliminate the need for a "skip navigation" link?