Evercookie stands for a JavaScript application programming interface that forms highly persistent cookies in a browser to identify a client, even after the cookies (standard or Flash, etc) have been permanently removed. In other words, evercookie technology recreates user’s cookie files after they were deleted. Evercookies have been developed after web developers realize the cookies have enabled really intrusive tracking and personalization. However, since they can be easily removed from the browser cache, the more persistent technologies – evercookies – have been created to track the user’s data.
In practice, evercookie is not just an actual cookie, but a shady mechanism for tracking them despite the user’s privacy settings, or else install the permanent cookies that can be recovered afterward. Additionally, they squirrel away the user’s data using various storage mechanisms, like Flash local shared objects, isolated storage, browser histories, HTML5 storage, etc.
Built by the supercomplex algorithms and smart technologies, the basic goal of the evercookie is to ensure data persistence, as it can be recovered and stored for re-use without the user’s consent.
There are different storage mechanisms evercookie uses to restore removed cookies, including:
- standard HTTP Cookies
- HTML5 Session, Local and Global Storage
- Local Shared Objects (Flash Cookies)
- Silverlight Isolated Storage
- storing cookies in Web cache / HTTP ETags / Web History and so on.
