An LED lamp or LED light is an electric light that produces light using light-emitting diodes (LEDs). LED lamps are significantly more energy-efficient than equivalent incandescent lamps and fluorescent lamps. The most efficient commercially available LED lamps have efficiencies exceeding 200 lumens per watt (lm/W) and convert more than half the input power into light. Commercial LED lamps have a lifespan several times longer than both incandescent and fluorescent lamps.

LED lamps require an electronic LED circuit to operate from mains power lines, and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The driver circuit may require special features to be compatible with lamp dimmers intended for use on incandescent lamps. Generally the current waveform contains some amount of distortion, depending on the luminaires' technology.

The LED lamp market is projected to grow from US$75.8 billion in 2020 to US$160 billion in 2026. LEDs come to full brightness immediately with no warm-up delay. Frequent switching on and off does not reduce life expectancy as with fluorescent lighting. Light output decreases gradually over the lifetime of the LED.

Some LED lamps are drop-in replacements for incandescent or fluorescent lamps. LED lamps may use multiple LED packages for improved light dispersal, heat dissipation, and overall cost. The text on retail LED lamp packaging may show the light output in lumens, the power consumption in watts, the color temperature in kelvins or a color description such as "warm white", "cool white" or "daylight", the operating temperature range, whether the lamp is dimmer compatible, whether the lamp is suitable for humid/damp/wet conditions, and sometimes the equivalent wattage of an incandescent lamp delivering the same output in lumens.

Before the introduction of LED lamps, three types of lamps were used for the bulk of general (white) lighting:

Considered as energy converters, all these existing lamps are inefficient, emitting more of their input energy as waste heat than as visible light. Global electric lighting in 1997 consumed 2016 terawatthours of energy. Lighting consumes roughly 12% of electrical energy produced by industrialized countries. New technological developments in light-emitting semiconductors, combined with the huge markets for displays and area lighting, encouraged the development of more energy-efficient electric lights.

The first low-powered LEDs were developed in the early 1960s, and only produced light in the low, red frequencies of the spectrum. In 1968, the first commercial LED lamps were introduced: Hewlett-Packard's LED display, which was developed under Howard C. Borden and Gerald P. Pighini, and Monsanto Company's LED indicator lamp. However, early LED lamps were inefficient and could only display deep red colors, making them unsuitable for general lighting and restricting their usage to numeric displays and indicator lights.

The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994. Isamu Akasaki, Hiroshi Amano and Nakamura were later awarded the 2014 Nobel Prize in Physics for the invention of the blue LED. The existence of blue LEDs and high-efficiency LEDs led to the development of the first 'white LED', which employed a phosphor coating to partially convert the emitted blue light to lower frequencies, creating white light. New LED lights entered the market near the start of the 21st century in the US (Cree) and Japan (Nichia, Panasonic, and Toshiba), and then starting in 2004 in Korea and China (Samsung, Kingsun, Solstice, Hoyol, and others.) In the US, the Energy Independence and Security Act (EISA) of 2007 authorized the Department of Energy (DOE) to establish the Bright Tomorrow Lighting Prize competition, known as the "L Prize", challenging industry to develop replacements for 60 W incandescent lamps and other lamps. Products meeting the competition requirements would use just 17% of the energy used by most incandescent lamps of that time.