I started wondering about this when I realized most websites I visit have white backgrounds, and I know that the screen is usually responsible for most of the battery usage. Since I can't change the background in those sites, I might at least switch my wallpaper to a black one.

Most (all?) phones need back-lighting to brighten the screen when needed. Since that back-lighting consumes battery, **is it correct to state that a white screen consumes energy at a faster rate than a black one?** *(assuming the same brightness level in the settings)*

I'm assuming that a white screen needs stronger back-lighting, but I don't know if it's the case.
['https://android.stackexchange.com/questions/5043', 'https://android.stackexchange.com', 'https://android.stackexchange.com/users/1926/']
On OLED, AMOLED and Super AMOLED screens: [Yes](http://techlogg.com/2010/12/ips-vs-amoled-vs-slcd-smartphone-displays-explained/1877)

LCD screens: [No](http://techlogg.com/2010/05/black-vs-white-screen-power-consumption-24-more-monitors-tested/17)
If your screen has an older standard lcd then this doesn't help at all. The backlight is still shining behind all those darkened pixels. You just can't see it.

If you have oled, amoled, super amoled, LED lcd, or I think even plasma then it does help to darken the screen because the light is generated specifically where it is needed. 

BTW there are fire fox plugins that reformat whatever page you are on to be dark. I don't remember the names, but I needed it when I was living in a studio apartment with my girlfriend and I was up all night on my computer while she was trying to sleep 20 feet away in the same room.