LCD Moniters help

[nymph4]

I know what a Moniters Contrast Ratio is it is the diferance between the Darkest Dark and the Lightest Light.

And you will see Ratings of  300 : 1

Now there is a Rating for the Brightness of a Moniter and it is given in  Candels Per Sqware Inch   I think.

And it will be given in   nT  and you will see Ratings of   200 to  400 nT.

What is this and how does this work??
All Moniters can be ajusted to how Bright they go or if you make it Dark so what is the Rating for  if you can ajust it  or is it telling you how  mutch you can ajust it??

[Dias de verano]

Candels Per Sqware Inch   I think.

nTs or "nits" is the non-SI name for candelas per square metre

There are no "inches" in the SI (the modern form of the metric system).

http://en.wikipedia.org/wiki/Luminance

http://www.wisegeek.com/what-is-a-lcd-monitor.htm