# What causes the pressure exerted by gas molecules on their container?

The gas molecules exert this pressure on their container. So, clearly, the cause is the gas particles themselves. Pressure in ${\text{N/m}}^{2}$ is defined as:
$\vec{P} = \frac{\vec{F}}{A}$,
which is the force $\vec{F}$ in $\text{N}$ exerted by a set of particles on a given surface area $A$ in ${\text{m}}^{2}$.