What does .C stand for?

What does .C mean?

C	Challenger Community » Sports
C	Celsius Academic & Science » Chemistry
C	Cubs Community » Sports
C	Caffeine Miscellaneous » Food
C	Capacitance Miscellaneous » Unit Measures
C	Convergent Academic & Science » Mathematics
C	Communicator Business » Positions
C	Cleanse Medical » Laboratory
C	Cyan Miscellaneous » Colors
C	Centigrade Academic & Science » Meteorology
C	Cylindrical Business » Products
C	Chanel Business » Products
C	Cilt International » Turkish
C	Cytosine Medical » Human Genome
C	Cytosine Academic & Science » Chemistry
C	Casper Miscellaneous » Names and Nicknames
C	Correctness Community » Educational
C	Curiosity Community » Educational
C	Complaining Community » Educational
C	Cello Community » Music
C	Cosmopolitan Community » Media
C	Confession Community » Religion
C	Cable Community » Media
C	Crushing Business » Products
C	Crabby Internet » Chat