Link building is one of the most important weapons for the SEO analysts but it has to be handled with a good understanding of the domain.The quality of links is also very important and the quality is indicated by the PR (Page rank) of a page. The higher the Page rank for an inbound link page, the higher the 'vote of approval' for your site.
When you're building links to increase your link popularity, who do you link to? The question of where to link to increase ranking can be confusing. Logical thinking is needed to achieve link popularity in a natural way. Some link builders uses softwares to increase inbound links which has nagative effects. To get good ranking and polularity try to manual submissions, as bing says "Good things come to those who wait and work smartly."
As a result of good Link building, page rank of website pages increases so search engine move website towards the top of the search result for your favourite keywords. Increase of traffic will increase selling of the products. The search engine rankings for all your major pages and keywords get a big boost by the effective execution of a Link Building campaign