A blank referrer increases privacy. Webmasters can use this noreferrer tool to prevent their site from appearing in the server logs of referred pages as referrer. The operators of the referred pages cannot see where their visitors come from any more.
A noreferrer 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 noreferrer's part is to suppress this information; when analysing their transfer logs, webmasters will track back to the noreferrer's URL instead of the original URL.
Technically, a noreferrer page is just a normal webpage with some scripting additions. The link to the noreferrer page supplies information about the target page. This information is evaluated by the noreferrer page, and using meta tags, the browser is told to visit the target page. For there is no direct linkage between the linking page and the target page, trackbacks to the linking page are not possible.