This photo of my photoalbum was taken in Tokyo.

Monochrome comes from the two Greek words mono (μoνο, meaning "only" or "alone"), and chroma (χρωμα, meaning "colour"). A monochromatic object has a single colour. In physics, the word is used more generally to refer to electromagnetic radiation of a single wavelength. In the physical sense, no real source of electromagnetic radiation is purely monochromatic, since that would require a wave of infinite duration. Even sources such as lasers have some narrow range of wavelengths (known as the linewidth or bandwidth of the source) within which they operate. In practice, filtered light, diffraction grating separated light and laser light are all routinely referred to as monochromatic. Often light sources can be compared and one be labeled as "more monochromatic" (in a similar usage as monodispersity). And a device which isolates light sources of a narrow bandwidth are called monochromators, even though the bandwidth is often explicitly specified, and thus a collection of wavelengths is understood. For an image, the term monochrome is usually taken to mean the same as black-and-white or, more likely, grayscale, but may also be used to refer to other combinations containing only two colors, such as green-and-white or green-and-black. It may also refer to sepia or cyanotype images. In computing, monochrome has two meanings:
* it may mean having only one color which is either on or off,
* allowing shades of that color, although the latter is more correctly known as grayscale.
A monochrome computer display is able to display only a single color, often green, amber, red or white, and often also shades of that color. The monochromatic scheme should be used with caution when designing a space. Certain monochromatic color concepts will appear rather monotonous, and some variety in the intensities, textures and forms should be used to give life to the interior. In film photography, monochrome is the use of black and white film. In digital photography, monochrome is the capture of only shades of black by the sensor. Originaly, all photography was done in monochrome until the invention of color film plates in the early 20th century.

Black-and-white is a broad adjectival term used to describe a number of monochrome forms of visual arts. Most forms of visual technology start out in black and white, then slowly evolve into color as technology progresses. "Black-and-white" as a description is also something of a misnomer, for in addition to black and white most of these media included varying shades of grey. Further, many prints, especially those produced earlier in the development of photography, were in sepia (mainly to provide archival stability), which gave a richer, more subtle shading than reproductions in plain black-and-white, although less so than color.