How LED's Work

Light Emitting Diodes (LED's) are made by pushing an electric current through two abutting insulators that have been doped by adding an impurity.
Silicon is an insulator with all its electrons tightly bound. If a small amount of antimony is added to it the extra atoms have spare electrons. (N Type) If another piece of silicon is doped with boron the additional atoms will have extra holes. (P Type). When the N and P type silicon is butted together spare electrons can flow from the P into the holes in the N silicon. When an electron fills a hole a small particle of light is given off. A battery pushing electrons into the P and emptying the holes in the N can keep a current flowing,creating the light source.

Modern LED's have developed this simple idea so it seems unrecognisable but the basics remain the same.
1. The LED must be supplied with Direct Current, and this must flow in one direction through the P type to the N type
2. Mains Voltage is 230 Volts and the driver has to convert this to a direct current to run the LED
3. Some drivers are specified in milliAmps and some (mostly LED tape) in a constant Voltage. The Volts and Amps are closely related but it is vital that only the driver specified by the manufacturer is used.
4. The join between the the semi conductors will break down if it is overheated so never exceed the power (milliAmps) specified.