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

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 backlinks to boost your site’s authority. Tier 1 links point directly to your site and have the most value. Tier 2 links support Tier 1 by linking to those backlinks, making them stronger