When comparing digital signage displays from different manufacturers you may come across the metric NITS and cd/m2 are both measurements of how bright a light source is.
cd/m2 represents candela per meter squared. Candela is a very old brightness metric that is based on “whale oil candles.” 1 Candela is the light emitted by one such candle, which were “standard” at the time.
NIT is a metric for measuring luminance, which is how much light an object emits. It comes from the Latin Nitere, which means “to shine.” NIT is equivalent to Candela (cd/m2), but is not part of the International System of Units.
1 NIT = 1 cd/m2
NIT and cd/m2 therefore represent the same thing and can be used interchangeably. The TV and display industry have been using the term NIT instead of Candela. cd/m2 is used in Digital Signage.