A backlinks campaign is used to give your Tier 1 and Tier 2+ properties some authority and relevance.
Tier 1 properties can be Cloud Sites, Social profiles, other entities that are closely related to the main site. They are usually high quality and authoritative – they are directly linking to the main website.
Tier 2+ are usually of lesser quality and not completely related to the main site but they have some relevance and authority, they are usually linked to Tier 1 sites and never the main site.Sometimes they are social profiles, link sites, comments and so on.
A backlinks campaign can help boost Tier 1 and Tier 2 properties which in turn will boost the main site by funnelling power, authority and search crawlers through the sites.