A body wave caused by a normal stress of a matter and as such have strain oscillations along the direction of p-wave propagation.
In terms of corpuscular structure of the matter the p-wave is characterised by the fact that particles of the matter are moving along the p-wave travel direction.
P-wave can propagate through gases, liquids or solids and moves faster than other body waves (almost twice).
See also
Physics / Mechanics / Continuum mechanics / Mechanical waves / Body wave
[ s-wave ]