The term of composting or rotting describes the decomposition of organic matter through destruents (microorganisms, annelids, sow bugs, and other small animals). The end product of this process is called compost (Latin: componere, to put together).
Compost is an important component of the upper soil layer. Its most important component is humus which is often very nutritious. Compost also has a huge water-storage capacity which helps plants to survive during dry periods. On the whole, finished compost is an outstanding fertilizer and an excellent soil amendment.
 
Composting is a natural process which takes place in the presence of oxygen (aerobic). In the absence of oxygen the material begins to rot. Anaerobic (oxygen-free) decomposition can be achived by putting green material in an airtight fermenter. Inside the container a transformation of the “greens”  into digested material takes place through the influence of bacteria. The digested matter provides, as a metabolite, particularly methane that can be used as vehicle fuel or as heating fuel instead of natural gas. Usually after the process the digested material can be composted aerobically.
 
Controlled composting

Garden compost:
We make use of composting in gardening, agriculture and waste management with the intention to transform organic substances into compost quickly and in a controlled way. An unwanted process of rotting (also because of the unpleasant smell) can be prevented through appropriate ventilation. A correct amount of moisture is just as important. Compost should neither dry out nor be too wet during the composting process. According to the van´t Hoff’s rule, the composting process can be speeded up through heat insulation (thermo compost bins).
 
Furthermore the mixture of source material is very important as the ratio of nitrogen to carbon must be balanced in order to provide the microorganisms with appropriate food. Generally, the right mixture consists of green and dried plants (e.g. hay, straw) or sometimes of cut twigs and litter. Coffee grounds lure worms and have a very positive influence on the composting process. Cooked leftovers or sweets involve the danger to attract rats, dogs, or raccoons. Compost is often wrongly described as fertilizer. But it is rather a source of energy for microorganisms. As a result of their vital functions metabolites emerge which serve higher developed plants as nutrients. The composting process can take place through bacteria and fungi as well as through annelids (e.g. in a worm bin).