What is meant by noise with regards to photography?

It is the digital equivalent of "grain" on film.

This is a pretty good explanation here: http://www.picturecode.com/noise.htm

Digital Noise & Color Distortion: Image noise is the variation of values in the detection process of your camera. Noise and color distortion (or digital noise) occurs most frequently in uniform color areas (i.e. skies and shadows) and is caused by temperature and/or sensitivity/ISO settings. With increased sensitivity, more light is required to avoid producing noise. With long exposures, cameras can also produce a different category of noise called hot pixels (stand alone color dots/pixels).

Noise Correction: The key to noise reduction (by either spot editing or noise filters and programs, such as Neat Image and Noise Ninja) is to correct the problem areas without affecting the overall quality and detail of the image. Freeware programs tend to produce lower quality results by creating a blanket "watercolor" or blurred effect and can also have limited settings for saving in highest quality.

Possible Solution: Adjust the ISO settings of your camera to 200 ISO or slower. Alternately, use slower speed film (25 to 200 ISO) for the least amount of noise and/or film grain.

There are typcially two types of noise associated with ISO sensitivity (digital) - Chroma (color) and luminance (detail). The higher the ISO sensitivity, the higher the noise level. Chroma noise is the color splotches that you see in higher sensitivities, luminance is the haziness, or "graininess" of detail, which has no color. The noise is a result of signal to noise of the A/D path, the higher you drive the signal (sensitivity), the more noise results on the A/D path to processing. Noise is a digital photography thing, "grain" is mostly associated with film where the actual silver nitrate/halide grain size changes with ISO.

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When the processor cannot gandle all the information (dim light for instance) some pixels will be created according to the algorithm from the processor maker. Tha's calle dnoise in digital.

Noise is a term for how pixelated the image or parts of an image can be. Alot of noise, would look very grainy.

The best way to SEE is by looking at the examples:

http://www.dpreview.com/learn/?/key=noise

Good luck.......

With regard to...

Unwanted sht on the neg or in the pixels.

how fuzzy th pic looks i believe