Here is where my stupidity shines...

[anut4disney]

what do you mean by noise?

 

[Ronda93]

This is shamelessly copied from DPReview:

Each pixel in a camera sensor contains one or more light sensitive photodiodes which convert the incoming light (photons) into an electrical signal which is processed into the color value of the pixel in the final image. If the same pixel would be exposed several times by the same amount of light, the resulting color values would not be identical but have small statistical variations, called "noise". Even without incoming light, the electrical activity of the sensor itself will generate some signal, the equivalent of the background hiss of audio equipment which is switched on without playing any music. This additional signal is "noisy" because it varies per pixel (and over time) and increases with the temperature, and will add to the overall image noise.

See the full article here.

 

[Kelly Grannell]

These pictures were taken at ISO 400.

Kodak Z760 - very high noise

Canon S2IS - very low noise