The structure of the page URL is the name of the intranet, the page type (community, page, library, or guide), the page ID, and then the name of the page.
For example: myfirm.synthesis6.com/page/121/benefits
One of our core goals in Synthesis 6 was to make it easy and safe to restructure your intranet by moving resources between communities, creating, renaming, and merging communities, and renaming pages, without worrying about breaking links.
The page ID URL structure supports this flexibility. The page name is not used in locating the page, so renaming a page will not break any existing links, even if you move it to a different community.