Composting involves mixing yard and household organic waste in a pile or bin and providing conditions that encourage decomposition.
Composting is a biological process during which naturally occurring microorganisms (e.g. bacteria and fungi), insects, snails, and earthworms break down organic materials (such as leaves, grass clippings, garden debris, and certain food wastes) into a soil-like material called compost.

 Composting 101
NCSU Composting info
NCSU all about Mulch and Compost
Clemson info on Compost
The History of Composting