Tiered link building organizes backlinks into two groups. Tier 1 links point...

https://eduardossmartcolumn.cavandoragh.org/broken-link-building-step-by-step-using-ahrefs

Tiered link building organizes backlinks into two groups. Tier 1 links point directly to your site and carry the most value. Tier 2 links support those Tier 1 links, boosting their strength and helping improve your rankings