Question

How are Galaxies, stars, and planets formed? In what order they're typically formed?

Answer 1

Hint :A galaxy may be a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and substance. The word galaxy springs from the Greek galaxias, literally "milky", a regard to the Milky Way.

Complete Step By Step Answer:
The order is galaxies, stars, planets.
There is no consensus on how galaxies are formed. Either they formed from the collapse of a cloud of matter under its own weight.
That collapse produces lumps of matter which further coalesce to make smaller lumps, which are stars. Planets are formed last, after stars, which further coalesce under their own weight, synthesize atoms of increasingly greater weight by fusion, before exploding and releasing cold heavy atoms like those found in planets and asteroids.
The second hypothesis is that galaxies were formed from lumps of matter that existed initially within the universe.
The way gravitation works is by accretion, that's from large to small scale, which is the opposite of what intuition would tell us. Humans build structures from small to large. That's because these structures are held together by electromagnetic forces, like chemical bonds, not by gravitational forces.
It is important to underline this fact because in astronomy especially, a day intuition is usually misleading. This is often thanks to the very fact that gravity is robust only at large scales (and at Planck scale) and these scales are so large compared to human scales that we've no direct experience of gravity, aside from weight, in our lifestyle.

Note :
The very first stars likely formed when the Universe was about 100 million years old, before the formation of the primary galaxies. Because the elements that structure most of planet Earth had not yet formed, these primordial objects – referred to as population III stars – were made almost entirely of hydrogen and helium.