Tiered link building uses two levels of backlinks to boost your site’s ranking....

https://www.bookmark-xray.win/tiered-link-building-helps-boost-your-website-s-authority-by-layering-links

Tiered link building uses two levels of backlinks to boost your site’s ranking. Tier 1 links point directly to your site and are high quality. Tier 2 links support those Tier 1 links, helping them gain strength and improve their value