Im confused on what the carbon cycle is. can I get a somewhat in depth definition?

Question

http://images.google.com/images?q=carbon+cycle&hl=en&ie=UTF-8&um=1&sa=X&oi=images&ct=title

http://www.cotf.edu/ete/modules/carbon/efcarbon.html

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CarbonCycle.html