Some people resort to building or joining private blog networks (PBN) to build incoming links as a technique to try and trick the search engines about the number of incoming links to their site but eventually they get caught. Note that this technique is against Webmaster guidelines.
Link schemes - Google Search Central...The best way to get other sites to create high-quality, relevant links to yours is to create unique, relevant content that can naturally gain popularity in the Internet community. Creating good content pays off: Links are usually editorial votes given by choice, and the more useful content you have, the greater the chances someone else will find that content valuable to their readers and link to it...
Bing Webmaster Guidelines...Link Schemes, Link Buying, Link Spamming : While link schemes may succeed in increasing the number of links pointing to your website, they will fail to bring quality links to your site, netting your site no positive gains. Manipulating inbound links to artificially inflate the number of links pointed at a website can lead to your site being delisted from Bing index....
Private Blog Networks (PBN): The Myths and The Risks...Building links is a powerful SEO tactic, and the right links can supercharge your rankings and organic visibility. However, earning backlinks isn't easy. At least it's not when you use tactics that don't violate Google's Webmaster Guidelines.
Some SEOs choose to use tactics against these guidelines to accelerate their website's organic growth, including using private blog networks (PBNs).
In this guide, we're going to dive deep into this controversial link building tactic and address some of the common myths surrounding it...