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Internet Marketing Guides » SEO Tips » Benefit: Outbound Links
Outbound links do reduce the PageRank and otherwise algorithmic weight of a page, but this is not always a bad thing, unless that link is unnecessary and leads to a dead site/page, bad neighborhood link or adds little to no value to the content. Typically though, it's natural to link to other sites, particularly when citing sources or referring to a subject matter where there may be a SME attributed (subject matter expert). It also pays to link out to reputable well-known sites because then you become associated with "good company" as far as SEO goes. There is no direct proof that this is the case, however it is natural, and search engines like natural - it's what works in the offline and also follows for the most part rules of society.