Link Building

Links were the first major ranking factor used by search engines. Google was not the first search engine to count links as “votes,” but it was the first search engine to rely heavily on link analysis (or the Link Graph) as a way to improve relevancy.
Despite the chatter around other signals, links remain the most important external signal for search rankings. But as you’ll find, some links are more valuable than others.

Quality of Links

Search Engine count all the links pointing at web sites (except those blocked using no follow or other methods), but they don’t count them all equally. They give more weight to the links that are considered to be of better quality.
What’s a quality link? It’s one of those “you’ll know it when you see it” types of things in many cases. But a link from any large, respectable site is going to be higher on the quality scale than a link you might get from commenting on a blog. In addition,  links from those in your “neighborhood”, sites that are topically relevant to your site, may also count more.

Number Of Links

Plenty of sites have found that getting a whole lot of  links can add up to SEO success. Even more so if your getting a lot of links from many different sites. All things being equal, 1000 links from 1 site will mean far less than 1000 links from 1000 sites.
Long ago, the sheer number of links used to be a far more important, but has decreased steadily as search engines learn how to better evaluate the quality of links.
Tactics such as viral linkbaiting campaigns, badges and widgets can all be effective at securing large numbers of links and something even search engine representatives have suggested.
But in your quest for links, don’t fire up automated software and begin spamming blogs. That’s a bad thing, in many ways, as we’ll explore later in this guide.