Tiered link building helps you boost your website’s ranking by creating links...

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

Tiered link building helps you boost your website’s ranking by creating links at two levels. Tier 1 links point directly to your site, giving it strength. Tier 2 links support those Tier 1 links, making them more powerful