Volatile organic compounds (VOC) are a relatively minor component of the atmosphere and yet are widely recognized to have important roles in air quality and climate. With the exception of methane, an important greenhouse gas, atmospheric VOC are primarily of interest because of their impact on other atmospheric constituents, including oxidants and aerosol. Most of the global annual VOC emission is from biogenic sources but biomass burning, fossil fuel combustion and industrial activities dominate in some regions. Each of these major sources can be further categorized, e.g., biogenic sources include plant chloroplasts, plant specialized tissues, microbes, and animals. The processes for removing VOC from the atmosphere include VOC surface deposition, VOC deposition to particles, and surface deposition of their oxidation products including oxidized VOC, CO and CO2. Regional to global atmospheric chemistry and transport models (CTMs) routinely include at least some VOC emission and removal processes but in a highly simplified form. Climate models have previously included just methane but as they evolve into more comprehensive earth system models, other VOC are being included although the sources and sinks may be prescribed or highly simplified.