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

https://www.emergbook.win/tiered-link-building-uses-two-levels-of-backlinks-to-boost-your-site-s

Tiered link building uses two levels of backlinks to boost your site's authority. Tier 1 links point directly to your site, giving it real value. Tier 2 links support those Tier 1 links, making them stronger and more effective