The data storage file, known as a Flash cookie, is used by websites to keep track of the user's preferences, such as the volume setting for a particular Flash application. But, just like browser cookies, Flash cookies have been co-opted by advertising networks and data aggregators to collect and store information about the browsing habits of internet users. And Flash cookies offer advertisers and data aggregators advantages over browser cookies, since they can store up to 100 kilobytes of information, while browser cookies can store only 4 kilobytes.

Flash Cookie

Notes from:
I Know Who You Are And I Saw What You Did: Social Networks and the Death of Privacy
By Lori Andrews
(page 24)

Csaba Osvath