Black

Black, just like white, is not a color.

Colors have three dimensions:
Hue, value and chroma.
Black is undoubtedly a hue.
As far as value goes, it is the darkest of all values on the scale, but it cannot vary in value like colors can. As soon as it is a bit lighter, it is not black any more.
And chroma, or intensity is fixed too, there is no blacker than black.

In painting, black has to be treated with a lot of respect. First of all, black easily dirties other colors. Also, black objects show a variety of color and values where the light hits them and it is important to look carefully to determine the hue of those colors. The most illuminated spot on a black object can be lighter than the darkest shadow on a white object.
I hardly ever use black (I believe there is still some paint in the one and only tube of black I ever bought), but rather mix the colors to interprete black with the three darkest transparent colors on the palette: Alizarin Crimson, Ultramarine Blue and Viridian Green. Real Black is only needed in the deepest of all accents, where no direct, nor reflected light hits the object.

White - is it a Color?

No, it isn´t.

Many years ago, when I studied oil painting with Sebastian Capella, I learned that White and Black are not colors.
Let me explain:
Color has three dimensions, hue, value and croma.
Hue, as in the tone like red, yellow, blue, etc.;
Value, referring to the degree of light or dark on a scale between black and white;
And Croma, as in intensity or purity of the color.

White fits within the first dimension, it does have a name, so it qualifies as a hue, but it does not have any variation in value, nor in croma. White will always be the lightest on the value scale and there is no more than one intensity - white is white.

Any color, added to another one, will change that color´s hue. For example, if you add red to yellow you get orange, blue to yellow makes green, and so on.
White, added to any other color does not change that color´s hue, it will only affect its value and diminish its intensity.

I don´t use pure white when painting a white object, pure white is rarely found in nature, there is always a hint of another hue present. Shadows and reflected colors will show us the white object in a lovely variety of colors! It´s only our brain which reads them as white.

Painting versus Photography

Even though photography and painting (or sculpting) have a lot in common with respect to the perceptive mind of the artist, I believe each of the two art forms has a different ideal or purpose.
Photographers capture the beauty of one moment in time, even when this moment depicts a subject in motion. A painter, who´s work takes a few hours to do, witnesses the subject matter over a longer period of time, and interprets a personal impression of it. This impression should be charged with the painter´s emotions and will give not only a more or less accurate account of the scene, depending on the style, but also a glimpse of the artist´s character.
For me painting in a realistic way does not mean trying to compete with what a a photographer can do, that would be a waste of time, as the camera can deliver so much more precision.