A referrer is URL data from an HTTP header field identifying the Web link used to direct users to a Web page. Referrers are used in statistical Web analysis and often integrated with marketing strategies and security methodologies.A referrer is also known as an HTTP referrer.
A referrer is commonly used to combat cross-site request forgery (CSRF), which is unauthorized or malicious activity from a trusted website user. The ease of disabling or forging referrers weakens security mechanisms. Some Web browsers, proxies and firewall software allow user referrer disabling. On the flipside, published referrer links allow bloggers to attract readers, enhance communication and expand blogging communities. However, this practice can lead to increased referrer spam. Most Web servers log all traffic, including referrer information, increasing privacy concerns. Thus, some Web servers are barred from receiving referrer information. Referrer data is often blanked out by Internet security applications.When the refresh command is used, most Web browsers do not send referrer data. The World Wide Web Consortium (W3C) discourages this practice.
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