Side Navigations create a group of links that can be displayed in a template side column. They can be edited using the _sidenav.pcf file. Side Navigations are edited in the WYSIWYG editor using a bulleted list of links. Add more _sidenav.pcf files to sub-folders to create navigations for those sections.
Use a Side Navigation to group links to pages in a section together. This makes navigating sub-sections of a site easy. On this page the side nav is being used to display all the links to pages in the underscore files section of the site. You can also use anchor links in the side nav to create a menu that jumps to section on a single page.
Enabling a Side Navigation
Side navigations must be enabled on a page using Page Properties. You can also select the template side column to display it in, left or right.