Light-Emitting Diodes (LEDs) require a lower voltage and a direct current (DC) to function, where as most places run on higher voltage alternating current (AC). Because of this, LED lamps require Drivers. The common household LED bulb comes with an LED Driver already built in, however there are a few forms of LED lights that do not come with internal drivers, such as certain tape lights and downlights. It is important to check the Datasheet of the LED product you are buying to check if you need an external LED Driver or not. If you do, there are three different types you can choose from depending on what you need.
Constant-voltage drivers are required if one output voltage is necessary.
Constant-current drivers are required if there is a range of output voltages necessary.
AC LED drivers are required if an AC voltage input is necessary.