Website navigation menus often include dropdown or flyout menus, where submenus are hidden by default and appear visibly when mouse users hover over or click a top-level menu item. These sorts of menus can major present accessibility challenges for many groups of users unless they are coded properly.
UW-IT Technology Accessibility Specialist Terrill Thompson has explored this problem in depth, and provides recommendations in his blog post Accessible Dropdown Menus Revisited.
The UW WordPress Theme includes a navigation menu that was specifically designed for accessibility. Website owners at the University of Washington are encouraged to use this theme.