* Gravity's Pull: Gravity pulls all matter towards the center of mass. In the Sun's case, this immense gravitational force pulls all its material, mostly hydrogen and helium, towards its core.

* Equilibrium: As the Sun's material is pulled towards the center, it creates immense pressure. This pressure, counteracting gravity, keeps the Sun from collapsing further. This balance between gravity and pressure is what gives the Sun its spherical shape.

* Hydrostatic Equilibrium: The state of balance between gravity and pressure in the Sun is called hydrostatic equilibrium. It's the same principle that keeps planets and stars spherical.

Think of it like this:

Imagine a large ball of dough. If you squeeze it from all sides, it will become round. The Sun is similar – the force of gravity is like squeezing the dough, while the pressure inside counteracts the squeeze, resulting in a spherical shape.

Important Note: The Sun is not perfectly spherical. Due to its rotation, it's slightly flattened at the poles and bulging at the equator, similar to how the Earth is an oblate spheroid. However, the difference in diameter between its poles and equator is very small compared to its overall size.