Cookie respawning is the process of recreating browser cookies from information in that has been deleted. With cookie respawning, companies can take information stored in flash cookies and use it to recreate a cookie in a browser. There are concerns that cookie respawning can violate a user's privacy and become problematic for the operation of the computer in the same way that any kind of cookie storage can ultimately challenge an operating system.
Techopedia explains Cookie Respawning
In recent studies, the use of cookie respawning has been found to be minimal, and companies that have been caught respawning have stopped. A Carnegie Mellon University study in 2010 looked at the use of "Local Shared Objects" (LSO), or "flash cookies," in Adobe Flash, popularly used by Web browsers, and saw that although cookie respawning may not be on the rise, a few fairly large sites did participant in this kind of reconstitution of cookies.
The possibility of cookie respawning is something that the tech community is taking seriously as experts continue to look at how data about Web users is tracked by companies on the Internet.