fr, tr, - Used by Facebook to deliver a series of advertisement products such as real time bidding from third party advertisers.
__utma - Collects data on the number of times a user has visited the website as well as dates for the first and most recent visit. Used by Google Analytics.
VISITOR_INFO1_LIVE - Tries to estimate the users' bandwidth on pages with integrated YouTube videos.
YSC - Registers a unique ID to keep statistics of what videos from YouTube the user has seen.
PREF - Registers a unique ID that is used by Google to keep statistics of how the visitor uses YouTube videos across different websites.