Tiered link building helps you build a strong backlink profile by layering...

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 helps you build a strong backlink profile by layering links. Tier 1 are your main backlinks pointing directly to your site. Tier 2 links support Tier 1 by linking to those first-tier pages