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

https://wiki-legion.win/index.php/How_Do_I_Find_Keywords_for_Link_Building_with_Google_Keyword_Planner%3F

Tiered link building uses two levels of links to boost your site’s rankings. Tier 1 links point directly to your site and are high-quality. Tier 2 links support those Tier 1 links, giving them more strength