No, light doesn't have inertia in the classical sense — inertia requires mass, and photons are massless. However, light does have momentum (p = E/c), which is purely derived from its energy and frequency, not mass. This is why light can exert pressure and why a box of trapped photons would have effective inertia as a system. The key distinction: momentum doesn't require mass, but inertia (resistance to acceleration) does. Light travels at c always — it can't be accelerated or decelerated, so the concept of inertia doesn't apply to individual photons.