Composting involves mixing yard and household organic waste in a pile or bin and providing conditions that encourage decomposition. The decomposition process is fueled by millions of microscopic organisms (bacteria, fungi) that take up residence inside your compost pile, continuously devouring and recycling it to produce a rich organic fertilizer and valuable soil amendment (seeUsing Your Compost To Amend Soils).
Sound complicated? It's really not. All you need to know about composting is a basic understanding of a few simple principles, and a little bit of elbow grease.