Tiered link building uses two levels of links to boost your website’s ranking....

https://wiki-neon.win/index.php/How_Do_I_Clean_Up_a_Messy_Backlink_Profile_from_Old_Campaigns%3F

Tiered link building uses two levels of links to boost your website’s ranking. Tier 1 links point directly to your site and are high quality. Tier 2 links support Tier 1 links, helping to strengthen their impact