A camera’s light meter looks at a scene and tries to render it as average reflectance or 18% reflectance), which is middle grey, a value considered right between pure black and pure white.
Black, being the darkest gray tone, is stripped of all light, while white is the lightest gray tone, exposed with too much light. In either case one really doesn’t see any detail because it’s either too bright or there’s no light.
Black and white images can only use dynamic range, texture, form, and tonality. It has no color to fall back on to make it interesting. But the term “black and white” is inexact because, really, there is only one pure black tone and only one pure white tone. In traditional film photography the dynamic range between black and white is almost infinite, while in digital images there are “only”253 shades of gray, still more than the eye can differentiate.
In reality, black and white photography is better described as “monochrome” photography. Until the 1880s, photographic processes used to print negatives — such as calotype, ambrotype, tintype, salt print and the albumen print — generally produced images with shades of brown, from dark chocolate to light taupe, or were rendered in depths of rich blues, or even in shades of silver.
Thus, the term monochrome encompasses all forms of “black-and-white” photography, producing images containing only one hue besides white, with neutral shades of one hue ranging from lightest to darkest.
I have posted selections of my images into Black and Whites, and Monotones for your enjoyment.