A private blog network (PBN) is a collection of websites built or acquired specifically to supply backlinks to a target site, with the intent of artificially inflating its rankings. Operators typically purchase expired domains that retain historical link equity, then publish thin content and link out to client sites. PBNs are explicitly against Google’s guidelines on link schemes and have been a target of algorithmic and manual penalties for over a decade. Despite this, they remain in use in competitive niches. The risks are significant: a manual action identifying a PBN as a source can cause the linked site to lose rankings abruptly. Legitimate SEO avoids PBNs in favour of earned, editorially placed links.