Why Outbound Links Are Important For SEO
There's no secret that search engines in general would like to to encourage linking to external sources from time to time. There are many reasons for this. Additionally, outbound links can provide much value to a user, so there is more incentive for a webmaster to link to other websites independent of what search engines might think.
Linking is What Makes the Internet a World Wide Web
The internet is probably one of the most useful tools available to any person. It's virtually an unlimited and accessible database of knowledge. It's also relatively easy to use thanks to certain components such as search functions and linking.
It Supports the Page Rank Algorithm
Page Rank is so a major factor when ranking websites, however it would never be possible if everyone decided to hoard page rank by not linking to other sources or using the NoFollow attribute.
What Do Others Think About External Links for SEO?
Virtually every great (successful) writer or blogger cites and/or refers other sources whether it's to be used for additional information or fact checking. There is a small bunch of non-savvy SEO writers who believe in the concept of Page Rank Hoarding and therefore choose to not link to other websites or always use the NoFollow attribute. This method is extremely poor practice, search engines don't want to rank selfish webpages or webpages that only ever link to non-reputable sources which is what a NoFollow is generally suppose to indicate.
The Ranking Function
There are several components of an outbound link:
- Anchor Text
- Link attributes such as the "title" or "rel"
- Relevance and Quality of the External Page (what's being linked to)
Best Practices and White Hat Tips
When and where to link to other sources should be a natural feel for professional writers and those who have been blogging for a long time. Formally, one should always cite a reference when either using quotes or presenting factoids for which are not commonly known or discovered by said writer. Other places to refer someone to somewhere else is when a new topic is briefly introduced but does not fit the scope of the page or content of the referring document.1
What to Avoid - Black Hat Tactics
Page Rank Hoarding is a big no-no. It's easily detectable by search engines and provides little to no value for readers. Good information is meant to inform people, and referring other quality sources to expand on a documents' current content is only natural and great for the reader.
Do not link too frequently. Most ranking factors are important because they often have a direct effect on user experience. A single website can not pretend to do it all and provide every bit of information possible without having to look elsewhere for expanded topics or clarifications. Even one of the encyclopedias in the world refer to external pages for more information on certain topics. On the flip-side, you can't just tell the reader to check hundreds of other places if you want the information you're looking.2
Common Questions About Outbound Links
"Should I Avoid Linking to Low Page Rank Sites? In Other Words, Will Linking to "Higher Quality" Sites Boost My Search Engine Optimization?"
In short, no. The external page's page rank is probably not really a good variable to consider mainly because it would discourage linking to smaller but still very useful webpages. I think other factors such as the CTR or Click Through Rate as well as the relevance of the page are much more important factors. I think that the quality of the external link is a small factor simply to reduce linking to poor quality pages, but it can not be too heavily weighted otherwise people would be put off from linking to small webpages even though they might be very useful.