How exactly do laser driver circuits work?

I already know that these circuits are used in lasers and regulate the voltage going to the light emitting diode but I do not know how. If anyone could give an explanation that would be understood by a noob that would be great!

I build one to specifications and tested it but don't understand the properties involved.

In its simplest form, a laser driver is a constant current source. In their more advanced forms, they stabilise the laser output with a monitoring diode and by keeping the temperature of the diode within strict limits.