what does an inverter do?

"Inverter For HP Jornada 720/728
Inverter Characteristics
This is a used inverter, tested to make sure it works.

The inverter will work with 720 or 728 model Jornada's. The inverter does not come with the screen shown in the picture."

The above ad/description is what was on an eBay item. I know I will feel the fool when I hear the answer, but what does an inverter do for the Jornada's? (eBay auction link: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120522052941&ssPageName=STRK:MEWNX:IT#ht_1832wt_1165).

Thanks!

an inverter (more specifically, a backlight inverter) converts a low voltage (usually around five volts) into a high voltage (several hundred thousand volts) current required to run a LCD backlight, because a LCD does not emit any light on its own, so needs a light source so you can see the display. The high voltage is not particularly dangerous as it is a very low amperage, and its the amps that kill, not the volts.

Good question...good answer.

However, a bunch of crank/funny answers popped into my head when I read the first post....

Go in the corner and stand on your head, Rich.