The world wide web is called a web for a reason. The concept is simple. Allow people to tie (link) documents together in any manner which they see fit. This gives readers capability to move from document to document as needed.
For example, you might have an article about diabetes which links to reports about drugs and blood monitors. These in turn may link to other documents which go into greater detail on symptoms, as well as results of medical studies and even FDA reports.
This is way web was designed to work. When a document (an HTML page) is properly designed, it references sources all over web as needed for many different reasons:
- to go into greater detail on subject matter - to provide alternate viewpoints - to give supporting evidence - to provide references used in creation of document - to list additional related information - to define terms
Properly used and maintained, external links add incredible value to a web site. Some webmasters do not like to include any external links (except for those carefully segregated on a "links page") because they believe that this causes visitors to leave their site. Their belief is they worked very hard to get people to visit, so why encourage them to leave?
These webmasters do not really understand web. Furthermore, they do not comprehend major reasons why people visit sites in first place, and why they return to same site over and over.
As a rule (with some exceptions) people surf web because they are looking for information or entertainment. These are primary uses of internet. Generally, surveys show that shopping or making any kind of purchase is not high on reasons people spend their time web surfing. No indeed, what they primarily want is to find out something. In fact, it is quite common for your average surfer to use a web site to research their purchase, then drive down to local store to pick it up themselves.
If you site has a good, well coordinated set of external links than you are giving your visitors access to additional information, which in turn provides them with an excellent reason to visit your site again. Yes, your visitor may surf elsewhere, but given that quality of external links is high, he will most likely return.
I have spent much time figuring out a good ratio of external links within a web site. I have found that a site can definitely have too many links to other sites. Too many links produces a whole series of problems:
- The internet is very active, so links tend to become obsolete very quickly. If you have a very large number of links in your site, you are ensuring that you will spend a great amount of time checking for link rot (http://www.internet-tips.net/Webmaster/maintlinkrot.htm). If you do not check your links often more and more of them will produce 404 errors, which will tend to cause visitors to NOT return to your site.
- The desire is to have quality links. This is what causes visitors to want to return. A large quantity of external links (especially a huge number on a single page) tends to make it seem as if links are of lesser quality. In other words, appearance is that you just slapped together a bunch of links without much thought.
- If a large number of your links are of subjects unrelated to your web site, then you most definitely have degraded, in eyes of your visitors, your site. You see, they came to your site because it contained information about a specific subject (or several different subjects). Linking to unrelated sites tends to dilute your site and chase away visitors.