Sitewide link
A sitewide link is a link that appears on every (or nearly every) page of a website, usually because it lives in a shared template area like the header, footer, sidebar, or navigation menu.
Because the link sits in a global template, a single placement can produce hundreds or thousands of individual links, one for each page on the host site. Common examples include a "Built by [Agency]" credit in the footer, a sponsor logo in the sidebar, or a partner link in the main navigation. Google has long understood this pattern and generally treats a sitewide link as a single editorial endorsement rather than thousands of separate votes, so the raw link count overstates its real value.
Sitewide links are not inherently bad. Footer links between a company and its parent brand, a theme developer credit, or a genuine sponsorship are all normal parts of the web. The risk comes from anchor text and intent. A sitewide link with a keyword-rich exact-match anchor pointing back to a money page is a classic footprint of paid or manipulative linking, and at scale it can trigger over-optimization flags or contribute to a manual action.
If you do place or accept sitewide links, keep the anchor branded or use a naked URL, and apply rel="sponsored" or nofollow when the placement is paid. For link prospecting, remember that a tool reporting a huge backlink count from one referring domain often just means one sitewide template link, so judge the relationship by the referring domain count and editorial context, not the link total.