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

https://wiki-spirit.win/index.php/Do_Social_Media_Links_Help_SEO_or_Is_It_Just_Traffic%3F

Tiered link building uses two levels of backlinks to boost your site’s search rankings. Tier 1 links point directly to your website and have the most value. Tier 2 links support your Tier 1 links, making them stronger