This article explains tiered link building by breaking it into two levels. Tier...

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

This article explains tiered link building by breaking it into two levels. Tier 1 links point directly to your site, boosting its authority. Tier 2 links support those Tier 1 links, making them stronger and helping your site rank better