Night Vision Googles are pair of optoelectronic devices in goggle form, designed to intensify existing light. In the ArmA-series the NVG's are part of the default loadout for conventional armed forces, especially western BLUFOR forces.
NV Googles and night vision devices in overall can also be used to observe Infrared light not visible by human eye normally.
Normal NVGs limit one's field of view, even if they are non-monocular. Notable exceptions include helmets used by jet pilots and CSAT Viper SOF.