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

https://touch-wiki.win/index.php/How_Do_I_Pick_High-Quality_Sites_for_Tier_1_Backlinks%3F

Tiered link building uses two levels of backlinks to boost your site’s authority. Tier 1 links point directly to your site and carry the most value. Tier 2 links support Tier 1 by linking to those backlinks, increasing their strength