The first frame of a 3D movie flyover of Tycho Crater on the Moon as seen by Kaguya. It displays the classic terraced crater walls and central peak of a complex crater.

Volcanism is any eruption of molten lava onto the surface.

The molten rock has a lower density than solid rock so it rises.

The rock on the surface of the planet or moon is bent backward, upward, and outward so the amount of material ejected is much larger than the projectile.

Large craters will have a central peak formed by the rock beneath the impact point rebounding upward and they may also have terracing of the inner walls of the crater from the collapsing of the crater rim inward.

Some of them have orbits that cross the orbits of the planets and moons.

When they get close enough to a planet or moon, they will be pulled in by the large body's gravity and strike the surface at a speed of at least the escape velocity of the planet or moon, i.e., faster than a bullet.

Most of the impact basins---craters measured in hundreds of kilometers---were made during this time.

It is noteworthy that about the time the heavy bombardment ended, life took hold.

Victoria Crater on Mars as seen by the Mars Reconnaissance Orbiter. It is a simple crater that has been partially filled in with sand---note the sand dunes on its floor.