The SI unit of wavelength is meter (m), and it is commonly represented by the Greek letter λ (lambda).

The distance between two consecutive compressions or rarefactions is called the wavelength.

Peaks are the highest points of a wave and are called crests, while valleys are the lowest points of a wave and are called troughs.

Compressions are regions where both density and pressure are high, while rarefactions are regions of low pressure where particles are spread apart.

The density and pressure variations in the graphic representation of a sound wave illustrate how these properties change with distance as the wave propagates through the medium, showcasing the compressions and rarefactions within the wave.