Outbound link is a url on your site that points to another website. While you should always be on a mission to get more sites to link to yours, you must not forget their polar opposites. (for instance a strategy deployed by SearchPlacementPro which are a proffesional SEO firm that specializes in Search Engine Optimization

By having outbound links from your site, you are in essence "voting" for the site you link to. This is part of the entire ranking algorithm process for all the search engines. The idea is, that if two sites are similar in content and design, a site with more links pointing to it would be considered more important by the search engine.

So then, why should you help out any other sites? Actually, by carefully linking to other relevant sites, you are increasing the relevancy of your own site.

Pretend you have a restaurant somewhere in the USA. Your site is a typical site that displays types of food, store location, hours, and coupons. You also know the power of outbound linking. For this case, you're going to link to 10 restaurat sites. Next, you link to 6 sites that are physically located in your city. Now, switch roles and view the site as a search engine spider. Navigate through the site, and determine that this site is about food. Then find a resource page and discover some well-known links . Next, find 6 links to sites located in your city.

So, as a happy spider leaving the site, you now know that the site you just visited is about food/restaurant (site content and links to the major players of the restaurant industry), and that it is located in your city.

Next, you visit one of the 6 sites listed as a resource in the site's city. You find the local address, and it has the same zip code as the restaurant site you're just at. Now you know how these two sites are related to each other.

Taking into account the fact that this local restaurant has also linked to major restaurat chains, as the spider,
I am lead to believe that this shop has relevancy to the zip code of your city.

So, as the spider returns the information to the database to be processed in the algorithm, it has pre-sorted some search results based on the links your site points to.

Another benefit of outbound linking is Geo Targeting, or Local search. There is a lot of speculation that local search is the next big trend in Search Marketing. While only time will tell, it won't hurt to have your physical address listed on your website for those who will be embracing local search.