Since the late 1990's search engines have used links as votes determining the web's opinion on what pages are more popular. The search engines themselves have the use of ilnk data, and complex algorithms create evaluations of sites and pages based on this information. Through links, engines can not only analyze the popularity of a website and page based on the number and popularity of pages linking them, but also by trust, spam and authority. The more trustworthy sites tend to link with other more trusted sites while spam sites receive very few links from trusted sources.
Link building is an art. It's almost always the most challenging part of an SEO's job, but also the one most critical to success. Link building requires creativity, hustle, and often, a budget. No two link building campaigns are the same, and the way you choose to build links depends as much upon your website as it does your personality.
As with any marketing activity, the first step in any link building campaign is the creation of goals and strategies. Unfortunately, link building is one of the most difficult activities to measure. Although the engines internally weigh each link with precise, mathematical metrics, it's impossible for those on the outside to know this data. SEOs rely on a number of signals to help build a rating scale of link value. One of the best ways to determine how well a search engine values a given page is to search for some of the keywords and phrases that page targets.
mozRank (mR) shows how popular a given web page is on the web. Pages with high mozRank (popular) scores tend to rank better. The more links to a given page, the more popular it becomes. Links from important pages (like www.cnn.com or www.irs.gov) increase a page's popularity, and subsequently its mozRank, more than unpopular websites.
A web page's mozRank can be improved by getting lots of links from semi-popular pages or a few links from very popular pages.
It takes time, practice, and experience to build comfort with these variables as they relate to search engine traffic. However, using your website's analytics, you should be able to determine whether your campaign is successful.
Success comes when you see increases in search traffic, higher rankings, more frequent search engine crawling and increases in referring link traffic.