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

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

Tiered link building uses two layers of links to boost your site’s ranking. Tier 1 links point directly to your main site, adding strong authority. Tier 2 links support those Tier 1 links, making them more powerful