Are galaxies expanding or contracting?

In most cases, they are contracting. Galaxies were born at the time of the Big Bang. A galaxy is basically a huge mass of stars swirling around each other, held together by their combined gravity. They swirl around slowly moving inwards kind of like water swirling around towards the drain of a sink. Just like a solar system, in which the planets are slowly being pulled towards the center (the Sun) while spinning around, suns in a galaxy are also being pulled towards its center by gravity. In most cases, galaxies are contracting, because the gravity of all the stars in that galaxy has a net gravity towards the center of mass (which is the center of the galaxy.) The energy of the Big Bang and the huge explosions that created all the stars in a galaxy keep the stars moving, for now, but they are all slowly contracting towards each other. The huge bulges in the centers of galaxies are evidence of this. Without contraction, the stars in a galaxy would spread out evenly, but the centers of galaxies have the highest densities of stars. That's because the stars in a galaxy are contracting towards the center of that galaxy, and most of the stars in close to the center. I say "in most cases" because sometimes galaxies collide and then a shitstorm ensues causing chaos and stars start spinning off in all directions. But soon enough (in galactic terms) the stars will soon be pulled back by gravity. Hope that helps :)