What is a dereferer?
Note: The term "referer" goes back to the misspelled word "referrer" in the technical specifications of the HTTP Protocol. It allows tracking back a visitor's origin and is an information of high potential in web statistics and analytics.
A dereferer is a webpage that is used to redirect users to different websites. Usually, web browsers send small pieces of information when following a link, including a so-called "referer". The referer is the URL of the page the user came from, giving webmasters the option to track back the origin of users visiting their sites.
The dereferer's part is to suppress this information; when analysing their transfer logs, webmasters will track back to the dereferer's URL instead of the original URL.
How does it work?
What's the use?
So you ask, why should I use a dereferer page when linking to other sites?
In 90% of all cases, there is no reason in using a dereferer - you've got nothing to hide, do you? But there are situations, where you do not want the url of the linking page to be published, i. E. if
- the linking page requires a valid login/session
- the URL of the linking page, or the linking page itself contains sensitive information (for instance, a session id)
- for some reason, you do not want your website's url being published
Who uses dereferers?
A typical use of dereferers are forums/discussion boards. Such boards contain large amounts of external links, and often require registration. Plus, many board administrators decide to keep their board's content private; they exclude search engine bots, and they are not interested in having some deep-links show up in any server logs. A dereferer enables board admins to hide their board from the eyes of the outer world.
An other classic is web-based email. Web-based email applications are quite complex, and pass a lot of information in their URL strings. Clicking on a link in an email message would normally result in transferring all those information to the visited link via the http-referer. Using a dereferer keeps the user's informations private.
There are numerous other situations a dereferer would be suitable for; almost all of them aim in more privacy while using the web.