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Why is visible light only a small part of the electromagnetic spectrum?

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A horizontal gradient bar displays the visible light spectrum from violet to red, labeled with corresponding frequency in terahertz, wavelength in nanometers, and photon energy in electron volts. — light When white light is spread apart by a prism or a diffraction grating, the colours of the visible spectrum appear. The colours vary according to their wavelengths. Violet has the highest frequencies and shortest wavelengths, and red has the lowest frequencies and the longest wavelengths.

Visible light is only a small segment of the electromagnetic spectrum because the term "visible light" specifically refers to the narrow range of electromagnetic radiation to which the human eye is sensitive.12

The electromagnetic spectrum encompasses an immense range of frequencies and wavelengths, extending from low-frequency radio waves to high-energy gamma rays. While all these forms of radiation share fundamental physical properties—such as traveling at the speed of light—they are categorized into different regions based on their distinct behaviors, interactions with matter, and the specific technologies used to detect them.34

The visible portion, typically ranging from about 400 nm to 700 nm, is defined by our biological capacity for vision. Other regions of the spectrum exist beyond these limits, but they remain invisible to us because our eyes lack the necessary sensitivity or because the ocular media absorb those wavelengths before they can reach the retina.152