Tiered link building helps boost your site’s authority by creating two levels...

https://wiki-velo.win/index.php/What%E2%80%99s_the_Safest_Way_to_Build_Links_Over_Time_Without_a_Penalty%3F

Tiered link building helps boost your site’s authority by creating two levels of backlinks. Tier 1 links point directly to your website from quality sources, while Tier 2 links support those Tier 1 links, making them stronger