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

https://mill-wiki.win/index.php/How_Do_I_Clean_Up_a_Messy_Backlink_Profile_from_Old_Campaigns%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