The type of wave in which particles move parallel to the wave motion is called a longitudinal wave.

Here's why:

* Longitudinal waves involve the compression and rarefaction of the medium the wave travels through. This means the particles of the medium oscillate back and forth *in the same direction as the wave propagates*.

Examples of longitudinal waves include:

* Sound waves: Sound travels through air, water, or solids by compressing and expanding the molecules in the medium.

* Seismic P-waves: These waves are the first to arrive during an earthquake and travel through the Earth's interior by compressing and expanding the rock.

Let me know if you'd like to explore other types of waves!