The wavelength of a transverse wave is often measured from the distance between two successive crests or two successive troughs.

Here's why:

* Crest: The highest point of a wave.

* Trough: The lowest point of a wave.

The distance between two crests or two troughs represents one complete cycle of the wave. This distance is the wavelength, often denoted by the Greek letter lambda (λ).

Let me know if you'd like more details on waves or any other physics concepts!