Introduction To Link Popularity BuildingLink Popularity is a search engine rating system that is based on the quantity and quality of inbound and internal links pointing to any particular web page. Inbound links include those that come from any other web site other than your own whereas internal links would be those that come from within the same domain name. Link popularity is also based not only on the "quantity" of links but the "quality or relevancy" of those links. Therefore to improve link popularity, it is not necessarily required to have a large number of links pointing to your site but rather a good number of quality links.
Think of any modern political election. A candidate will have a campaign platform which will include their value and belief system, the political issues they will tackle, and promises they make once in office. This can be compared to on-page web site optimization. A political candidate may have an excellent campaign platform however unless no one is running against him or her, they will need credible endorsements in order to have a chance of winning the election.
Web sites are the same in that they can be thoroughly optimized, but without credible endorsements (inbound links), they will have a more difficult time gaining prime search engine visibility. When another site links to yours, a search engine looks at "who" is linking and evaluates what kind of authority they have as well as what they are saying in the link (anchor text).
With this picture in mind, a web site that has any competition at all will need strategic, quality, relevant inbound links to compliment their on-page optimization efforts.