Tiered link building uses two levels to boost your site’s ranking. Tier 1 links...

https://www.4shared.com/office/BIObF2h6fa/pdf-72309-44204.html

Tiered link building uses two levels to boost your site’s ranking. Tier 1 links point directly to your site and have the most impact. Tier 2 links support those Tier 1 links by linking to them, making the overall link profile stronger and more natural