Low-pressure sodium (LPS) is a type of gas discharge lamp that produces light through the excitation of sodium vapor. It operates at low pressure, which allows for high efficiency and a long lifespan. The light emitted is primarily monochromatic, appearing as a yellow-orange hue, making it easily recognizable in street lighting and outdoor applications. LPS lamps are known for their energy efficiency and low maintenance costs. They are often used in urban areas for street lighting, as they provide good visibility while minimizing light pollution. However, their limited color rendering ability can make it difficult to distinguish colors under their light.