Wavelength is the distance between two consecutive peaks or troughs in a wave. It is a key characteristic of waves, including those in light, sound, and water. Wavelength is usually measured in meters and is inversely related to frequency; as the wavelength increases, the frequency decreases, and vice versa. In the context of light, different wavelengths correspond to different colors. For example, red light has a longer wavelength than blue light. Wavelength is crucial in various fields, including physics, engineering, and communications, as it affects how waves interact with materials and how they are transmitted.