Here's a breakdown:

* Gravity is a force of attraction between any two objects with mass. The more massive the objects, the stronger the gravitational pull.

* Stars are incredibly massive – they contain vast amounts of hydrogen and helium gas.

* The immense gravity of a star pulls all its matter inward, creating a huge amount of pressure at its core.

* This pressure is so intense that it triggers nuclear fusion, a process where hydrogen atoms fuse to create helium and release enormous amounts of energy. This energy outwards counteracts the inward pull of gravity, creating a stable balance.

Think of it like a tug-of-war: gravity is pulling inward, and the outward pressure from nuclear fusion is pulling outward. The balance between these forces keeps the star from collapsing or exploding.