Emission may refer to:

• Flue gas, also:
  • Exhaust gas, flue gas occurring as a result of the combustion of a fuel
• Emission of air pollutants
• Emission of greenhouse gases, a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range
• Emission (electromagnetic radiation), the process by which the energy of a photon is released by another entity
• Emission (radiocommunications), the radio signal (usually modulated) emitted from a radio transmitter
• Emission coefficient, a coefficient in the power output per unit time of an electromagnetic source
• Emission factor
• Emission line, or "spectral line", a dark or bright line in an otherwise uniform and continuous spectrum
• Emission nebula, a cloud of ionized gas emitting light of various colors
• Emission spectroscopy, photoemission spectroscopy, flame emission spectroscopy and other types of spectroscopy
• Emission standard, requirements that set specific limits to the amount of pollutants that can be released into the environment
• Emission theory, a competing theory for the special theory of relativity, explaining the results of the Michelson-Morley experiment
• Emission theory (vision), the proposal that visual perception is accomplished by rays of light emitted by the eyes
• Emissions trading, a market-based approach used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants
• Ejaculation, the ejecting of semen from the penis; also, specifically:
  • Nocturnal emission, ejaculation experienced during sleep
• Light emission
• Thermionic emission, the flow of charged particles called thermions from a charged metal or a charged metal oxide surface, archaically known as the Edison effect
• Noise emission; see Noise
• Exhalation, especially where the velocity of exhaled air can influence the harmonic generating properties of a vibrating body, such as the reed of a musical instrument like the saxophone

Der Begriff Emission (lat. emittere „aussenden“) bezeichnet:

• Physik: die Aussendung von Wellen oder Teilchen; siehe Emission (Physik)
• Ökologie: eine Abgabe von Substanzen an die Umwelt; siehe Emission (Umwelt)
• Bankwesen: die Ausgabe/Einführung von Wertpapieren bzw. Geld; siehe Emission (Wirtschaft)
• Postwesen: die Ausgabe/Einführung von Briefmarken; siehe Emission (Briefmarken)

Emission kan vara

• ett begrepp inom finansmarknader, se emission (värdepapper)
• ett begrepp inom strålningsläran, se spontan emission, stimulerad emission och emissivitet
• ett begrepp motsvarande utsläpp från bilar eller fabriker

Emisja to ogólnie działanie polegające na przenoszeniu jakiegoś elementu układu do jego otoczenia. Czasem może się wydawać, że emisja polega na tworzeniu czegoś przez układ.