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

https://dibz.me/blog/strategic-insights-crafting-an-effective-tiered-link-building-campaign-959

Tiered link building uses two levels of backlinks to boost your site’s ranking. Tier 1 links point directly to your site and carry the most value. Tier 2 links support those Tier 1 links, making them stronger and more effective