Tiered link building uses two levels of links to boost your site’s authority....

https://www.bestbookmarks.win/tiered-link-building-uses-two-levels-of-links-to-strengthen-your-website-s

Tiered link building uses two levels of links to boost your site’s authority. Tier 1 links point directly to your website, while Tier 2 links support those Tier 1 links, making them stronger