What are the key characteristics of a wave, and how are they defined based on its diagram?

The image displays a diagram illustrating key characteristics of a wave.

• Crest: This is the highest point of the wave.
• Trough: This is the lowest point of the wave.
• Amplitude (A): This is the maximum displacement of a point on the wave from its equilibrium (resting) position. It is measured from the equilibrium line to a crest or a trough.
• Wave height: This is the vertical distance from a trough to a crest. It is equal to twice the amplitude ($2A$).
• Direction of wave propagation: This indicates the direction in which the wave, and its energy, is traveling.