Most search engines work around a similar model in which incoming links are one of the most important element in determining a page or site's quality. The higher quality a page, the higher ranking it receives in the engines. Make no doubt about it, all incoming links help boost a page's ranking in most search engines, but some links "count" more than others. Generally speaking, sites with higher rankings provide more authority than those with low rankings.
Page Authority Matters
A site, or page's, authority is based on a number of factors, but incoming links are among the most important. The more incoming links a page attracts, the more authoritative it is considered and this usually leads to higher rankings in the engines. No search engine's algorithms are known completely, but, along with good coding and clever use of search engine optimization, incoming links rate extremely high.
Effective SEO goes a long way in facilitating search engine standings, and is easy to incorporate with a little practice. Successful SEO can also attract powerful backlinks from other websites and blogs. You'll want to hire a full-fledged SEO firm to handle the heavy lifting, but you can help your link building efforts by filling in your page titles and meta descriptions, and taking a moment to punch-up the on-page text to include some of the keywords and phrases you wish to focus on.
Don't go overboard or try to fool the engines though - they catch on quickly and you might be penalized for your attempt.
Strive For Link Quality
Some of the best quality backlinks come from other websites that are highly related to your site or subject matter. A high-quality link will also send decent traffic as the potential visitors who see your link already trust the source (and have probably even opted-in to receiving correspondence relating to your site), so they are predisposed toward clicking on the link. They are also among the easiest to convert once you get them to your site.
Although you can buy backlinks for ranking purposes, this is highly frowned upon by Google. Note that this is different from advertising on a site, either directly or through an affiliate system. Buying backlinks may temporarily improve your standing in the search engines, but it might also hurt you in the long run. And, unless you're being extremely careful, you also lack control as to where these paid links are coming from, and there are some really bad neighborhoods out there. Since too many links from "bad neighborhoods" can detract from your rankings; youll want to acquire incoming links naturally wherever possible.
You can do this through good coding and a little SEO, but your site must offer something others need for it to be useful (and get linked to!). Be sure to deliver with your sites content but also offer to write free articles including your URL, and become active in communities relating to your subject matter. Become an authority by answering questions and being helpful, not by pushing your site at every opportunity.
Good links can come from anywhere - someone might link to you in a private e-mail or on a blog post, or call attention to your site in a forum - but great links come from relevant sites with high rankings in "good neighborhoods that send traffic. These are the organic links that often rate higher over time.
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In your opinion is it still effective to get links from high quality sites even if it is in an unrelated catagory. What do you think about no-follow links. Are the still a good link to get or should I spend my time with do-follow links.