Zombie Cookie

What Does Zombie Cookie Mean?

A zombie cookie is an HTTP cookie that returns to life automatically after being deleted by the user. Zombie cookies are recreated using a technology called Quantcast, which creates Flash cookies to trace users on the internet. The Flash cookies are then used to recreate browser cookies, becoming zombie cookies that never die.


Techopedia Explains Zombie Cookie

Websites may use Flash cookies for tasks such as setting volume levels and tracking users with a unique ID. When a user tries to delete cookies after visiting a website with Quantcast technology, the user ID is stored in the Adobe Flash player storage bin. The Quantcast program retrieves the user ID and reapplies it to keep track of the user’s browsing history.

The main purpose of zombie cookies is to store the personal information of web users for online marketing activities. Quantcast technology is used by many websites to measure website traffic and gather personal profiles of website visitors. Websites that used Quantcast were sued in 2010 on the grounds that they had violated federal computer intrusion laws. The court order required that all prosecuted website companies erase the users' personal information and stop collecting that information in the future.

Modern browsers include control settings that allow users to decide whether they want to accept cookies or to opt out. Browsers like Firefox provide an option to delete Flash cookies as well as zombie cookies through the add-on settings.


Related Terms

Latest Home Networks Terms

Related Reading

Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…