referrerURL

A referrer URL, also known as a referring URL or HTTP referrer, is a piece of information passed from a web browser to a web server. It indicates the address of the webpage that the user was on immediately before navigating to the current page. Essentially, it tells the current website where the visitor came from.

This information is transmitted via the HTTP Referer header in a web request. Websites can use referrer URLs for various analytical purposes. For example, they can track which external websites are sending them the most traffic, understand user behavior by seeing the path users take through their site, or identify referral partners. This data is valuable for marketing, SEO, and website performance analysis.

However, the Referer header is not always sent. Users can configure their browsers to disable it for privacy reasons. Additionally, some security software or firewalls might strip this information. Secure connections (HTTPS) to insecure connections (HTTP) will also prevent the Referer header from being sent to maintain security. Consequently, referrer data should be considered a valuable but not always complete source of information. It is important to note that the spelling "Referer" is a historical typo that has persisted in the HTTP specification.