We are not doing all of this chapter and we will not do too much with pulse type waves. We will mostly concentrate on the sinusoidal wave of section 16.3. Section 16.7 extends the discussion to 2 and 3D while 16.8 discusses energy and intensity of a wave.
In the video below, Prof. Leblond alludes to the E&M wave which we will see next week.
There are many different type of waves: sound, waves in water, pulse on a string, light, and many more. The basic definition of a wave is “It is a disturbance from equilibrium that propagates with time from one region of space to another."
In the slow motion movie below we see water which is made of a very large number of atoms. When a droplet falls on the surface it creates a disturbance which propagates away from where the droplet fell. That is the wave. If you have a single droplet falling, we get a single non-repeating disturbance. We call that a pulse. If your faucet was leaking a droplet every second, we would get a periodic repeating wave in the water.
A wave varies in space with wavelength
The wavelength is the distance between peaks. Note that position, x, not the time, is on the horizontal axis. This is important not to confuse this figure ("Graphical Representation of Wave") with the oscillation graph ("Graph of an Oscillatory Motion").