DoubleClick is a subsidiary of Google that develops and provides Internet ad serving services. Its clients include agencies, marketers (Universal McCann Interactive, AKQA etc.) and publishers who serve customers like Microsoft, General Motors, Coca-Cola, Motorola, L'Or?al, Palm, Inc., Visa USA, Nike, Carlsberg among others. DoubleClick's headquarters are in New York City, United States. DoubleClick embeds code in its partners websites that cause the web visitors browser to send a notification back indicating a visit to the site.

This SonicWALL signature identifies DoubleClick HTTP traffic.