Here's why:

* Longitudinal waves are waves where the particles of the medium vibrate parallel to the direction the wave travels.

* Compressions are areas where the particles are close together, creating high pressure.

* Rarefractions are areas where the particles are spread out, creating low pressure.

Examples of longitudinal waves:

* Sound waves: Sound travels through air as compressions and rarefactions.

* Seismic P-waves: These are the primary waves produced by earthquakes, also traveling through the Earth's crust as compressions and rarefactions.