LED lights have been around since the late 1960's, although Electroluminescence, which is the working principal of the light, was discovered around the turn of the century. LED stands for Light-emitting Diode which is a two-lead semiconductor light source. What makes this type of light so important is the fact that in comparison to incandescent lighting, it consumes far less energy, it lasts longer, the physical size is smaller, and you can switch at high speeds. It is for these reasons alone that the future of cinema lighting is bound to fully embrace this technology.
In the past, incandescent lights have served us well on film cameras and is still preferred to use when using the medium, but when it comes to digital cameras and video equipment, there has always been room for a more appropriate light source to match the electronic nature of the cameras and their sensors since they were invented in the early 1980's. In the late 1980's and into the 1990's, digital cinematography was experimented with by all sorts of film makers, but it wasn't until the late 1990's that a break through would emerge. The emergence of HDCAM based recording at 1920 x 1080 via CCD technology was a game changer and in the early 2000's, two films were released that experimented with this new technology. Those two films were Star Wars II: Attack of the Clones and Once Upon a Time in Mexico. Both films used LED lighting to light they're subjects in various scenes through out the films and the result looked better than expected.
Since the early 2000's, digital cameras have come a long way and the sensor technology has only gotten closer to capturing the essence of film cameras. In the present day, most productions shoot on high-end HD cameras that record RAW at 2K, all the way to 5K. Along with that, we are seeing LED technology grow and expand in many exciting ways to match the ever changing nature of digital cinematography. Now-a-days you can rig a whole lighting set-up to a control panel or remote control and change settings, directions, and power down all at the click of a button or the turn of a dial. There's also something to be said about the physical robustness of these newer LED lights with the added benefit of low cost production and the low cost to purchase.
In an ever-growing world where the necessity for energy conservation is growing along side the population, technology like LED lights have a tremendous chance of sustaining and even taking over as the light source of the future, which we have already seen signs of. This is no different for the world of digital cinema.