Tier 1 links are your direct authority boosters while Tier 2 links help them...

https://rowansbestthoughtss.huicopper.com/what-are-good-tier-2-link-types-besides-blog-comments

Tier 1 links are your direct authority boosters while Tier 2 links help them stay relevant. Using Ahrefs to monitor your backlink profile helps you see how these layers push rankings up without overdoing it