Why is inner core of the earth solid?

Inner core is solid and outer core is liquid

Before we start, i want you to watch and hear this question carefully.

The outer core is in liquid state while the inner core is in solid state Why? I mean the inner core is hotter than the outer core but the inner core is solid and the outer core is a liquid. Why, why is it like that?

This question is part of Geophysics. A geophysicist is someone who studies the Earth using gravity, magnetic, electrical, and seismic methods.

So going back to the question, we know that Earth´s inner core and outer core are both made of an iron-nickel alloy and that's why the core is also called as the nife layer, where the Ni stands for nickel and Fe stands for iron. And we also know that Matter can exist in one of three main states that is solid, liquid, or gas and for that we need the right temperature and pressure conditions.

solid to liquid and liquid to solid

 Most materials, including iron and nickel, change from liquid to solid at lower temperatures or higher pressures. It´s easy to imagine going from a solid state to a liquid state at higher temperatures because we are all familiar with ice melting on a warm day. But why do materials change from liquid to solid at higher pressure? In almost all materials apart from water, atoms are packed closer together in the solid state than in the liquid state. So when you squeeze the atoms together with high pressure the material changes from liquid to solid. Now when you understand this, now think of this as you go deeper in the Earth both temperature and pressure increases. Although the inner core of the earth is very hot, but it is solid because it is experiencing very high pressure. The pressure is so great that the metals are squeezed together to not be a liquid. The pressure in the outer core is not high enough to make it solid. And this is why,  the outer core is in liquid state while the inner core is in solid state despite of the fact that the inner core is hotter than the outer core.