Referrer Input for Contact Form 7 is a free WordPress plugin designed to enhance the functionality of the popular Contact Form 7 plugin. This addon introduces a new input field that captures the URL of the webpage the user visited prior to accessing the contact form. The plugin utilizes JavaScript to populate this field on the client side, ensuring compatibility with caching plugins, allowing for seamless integration without server-side interference.

Once installed, users can easily add the referrer input field to their forms by clicking the 'Referrer' button in the form editor or by using a shortcode. This field captures the last page visited by the user on the site, providing valuable context for messages received through the contact form. By using a simple mail-tag, users can retrieve the referrer URL in their email notifications, which aids in understanding customer inquiries and feedback.