Definition - What does Flash Cookie mean?
Websites may use flash cookies to improve the user's experience, but these cookies do pose privacy concerns because they can be used to collect information about how people browse certain websites.
Flash cookies may also be referred to as local shared objects (LSO).
Techopedia explains Flash Cookie
Another issue with companies using flash cookies on their websites is related to their relative permanence. Some websites are now reviving conventional cookies, and using the more tenacious flash cookies as markers, a process known in the IT world as re-spawning. This raises more questions about whether flash cookies should be regulated as potential tracking devices.