Why Links Are Important for SEO
TweetBack in the early days of Internet marketing search engines used meta tags, meta keywords, and a lot of on-site factors to rank pages in the results (SERPs). Then Google came along and found a better way to do it that depended in large part on links. It's not just how many links you have, but the quality of the links that matter. Let's take a look at the two main reasons that links are important for your SEO strategy.
Gets Your Site Indexed
This part of the equation is overlooked but I wanted to list it first to show just how important it is. When you create content, you want to make sure that those pages get indexed by the search engines so you can show up in the SERPs. More reasons on why content is important, it gives your site authority and pagerank that you can sculpt to the pages that you want to show up for the keywords that you are targeting.
The more links you have pointing to your site, the more times that a spider will leave someone else's site to crawl yours. Link variation plays a big role here. If you are getting all of your links to one page then the spider starts in the same place each time and goes from there. If you get links deeper into your site, the higher the chance that you are going to get more pages ranked. That is why when getting links to your site do not only worry about a few pages, but get links deep into your site so more of your pages show up in the index.
What Your Site is About
The anchor text of the links pointing to your site tells the engines what your site is about. It is very important to getting a high ranking, but the search engines know just how important it is too. That is why they are so against paid links, because that is just a way for marketers to game their system and get their site ranked high even if they don't "deserve it" naturally in the search engine's eyes.
Say there are two sites are competing for the top spot for a certain keyword. One of them has 25 backlinks with the keyword as the anchor text and the other has 100 links of the generic site name or URL. Most likely with all other things being equal, the one with the targeted anchor text is going to win out.
Getting backlinks from relevant websites is also important. It used to be that you could get any old site to link to you and Google would give you plenty of love. Now the spiders are smart enough to realize that a golf blog linking to a golf tip site is a better indicator of relevance than a link to a golf tip site from one about dinosaurs. The link from the dinosaur site isn't worthless, but it isn't as powerful as from a relevant niche.
Don't get me wrong, you are going to want to concentrate on getting your keywords in the anchor text of links pointing to your landing pages, but don't make that the 100% focus of your off-site optimization.