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

https://www.slideserve.com/richard_russell21/what-should-i-use-for-tier-1-links-if-i-want-to-rank-a-landing-page

Tiered link building uses two levels of links to boost your site’s rankings. Tier 1 links point directly to your site, while Tier 2 links support those Tier 1 links