Every single person that has a web site would like to have more links coming to their site. Links to your site can be thought of as the roadmap for the traffic through the web. Although there are millions and millions of Internet users not a single one will find their way to your website unless it is clearly indicated in the road map. So it could be said that if your site does not appear on the road map then no traffic will appear at your site.
Links are important to the search engines because they will use a mathematical formula based on the number and quality of links into your site to determine if you'll appear on page 1 or on page 1001. I mentioned the quality of links as being part of the formula and the quality of links is very important to your ranking and your placement in search results. The link from an authority site could be thought of as a six lane highway covid that leads right up to the front door of your website. Reciprocal links or links from a link exchange program could be thought of as a narrow back lane that no traffic will ever find its way through.
The traffic that would come from social bookmarking sites will most often very highly targeted traffic. The tagging system at these social sites that will be appended to your link will ensure that anyone clicking on your link will know exactly where it is that they're going and why they are interested in getting the information that is there.
This is like the magazine rack at the checkout of your local supermarket. You have already selected everything that you need and the now waiting in line to check out that one of the headlines on a magazine catches your attention and you pick it up to find out more. So in social bookmarking sites the tagging of your link creates the interest and they are compelled to take the next step and visit your site to satisfy their thirst for knowledge or their curiosity.
The power of social bookmarking could be likened to "high tech word of mouth". This is the sharing of web sites with personal recommendations from people on the sites that you trust, people that you have a common bond with, people that have similar tastes, and likes and dislikes that a similar to your own.
If I tell you through an advertisement that I have developed a process that will improve your health and extended the duration of your life then there is a one in 100 chance that you'll go to the site and check out for yourself the validity of my statement. If you are told the same thing through a social site there is a one chance in three that you'll go and check out the site. Social sites have become the holy grail of the Internet marketers. Getting product recommendations that appear to come from social sites is something every Internet market dreams of because most social sites have some form of restriction on advertising. If you are clever enough to achieve quality links from the social sites to your web page you will have a guaranteed flow of traffic similar to an expressway.