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

https://wiki-zine.win/index.php/Can_I_Do_Tiered_Link_Building_Myself_or_Do_I_Need_an_Agency%3F

Tiered link building uses two levels of links to boost your site’s ranking. Tier 1 links point directly to your site and provide strong, high-quality signals