What is Site-Wide links In SEO?

A site-wide link is a link that would appear on all (or many) pages of the same website, with the exact same anchor text, title, target, etc...

a sitewide link is one that appears on most or all of a website's pages. ... You can also get sitewide links from being mentioned in the footer of a site if the site uses a template where the same footer is used for every single page.