Generally, people are concerned as to what to put into their composting system. 

YES LIST Animal manure Cardboard rolls Clean paper Coffee grounds, filters and Tea bags Dryer and vacuum cleaner lint Eggshells Fruits and vegetables Grass clippings, Yard trimmings, and Leaves Hair and fur Hay and straw Houseplants Nutshells Sawdust and Wood chips Shredded newspaper Wood chips Wool rags and Cotton rags

NO LIST Charcoal ash     Might contain substances harmful to plants Dairy products     Create odor problems and attract pests         Diseased or insect-ridden plants      Diseases or insects might survive and be               transferred back to other plants Fats, grease, lard, or oils      Create odor problems and attract pests        Meat or fish bones and scraps       Create odor problems and attract pests Pet wastes (e.g., dog or cat feces, cat litter)       Might contain parasites, bacteria, germs,                  pathogens, and viruses harmful to humans Yard trimmings treated with pesticides      Might kill beneficial composting organisms

Clip out the lists below as a reminder of what does and does not go into your compost system.