Anyone know what an "inverter board" is beside regard to a laptop?

The screen on my laptop went black (seems like a bulb or something is out or loose) since I can see what is there if I shine a flashlight into the side of the surface...I was told to renew the inverter plate but seems same anyone WHO can/will (stores) wants to charge me an arm and limb for something that doesn't seem to be that big a deal...diagnosis fees etc..