When organic material decomposes under anaerobic conditions, it produces biogas which is a mixture of methane (CH4) and carbon dioxide (CO2) with small quantities of hydrogen, nitrogen, carbon monoxide and other compounds. Biogas can be used as a fuel source for cooking, heating, producing light or even fueling a generator. A methane digester is a device used to produce and capture this biogas. There are many designs for methane digesters ranging from large and complex to small and simple. This document will cover 2 main types of digesters: batch digesters and flow-thru digesters; and 2 main types of gas collectors: tube collectors and floating collectors.