PBN (Private Blog Network)

PBNs are often built on expired domains that still have backlinks from their previous life. The owner fills them with thin content and uses them to place links to their own or clients' sites. Some are sold as a service, sometimes presented as ordinary guest posts.

They fall under link spam in Google's spam policies, which cover creating links primarily to manipulate rankings, including buying and selling links that pass ranking credit. Sites that benefit from link spam risk having those links ignored or receiving a manual action, and a network discovered by Google can lose its value overnight.

Warning signs that a link offer involves a PBN include:

• Sites with little real traffic covering unrelated topics.
• Fixed-fee placements promised on “high authority” sites.
• Many sites with similar designs, owners or hosting.
• Content that exists only to hold links.