Stars begin as huge clouds of dust and gas that contract and heat up to the point of nuclear fusion.

Here's why:

* Gravity: The cloud's own gravity pulls the particles towards each other.

* Contraction: As the cloud contracts, the particles get closer together. This makes the cloud denser and hotter.

* Nuclear Fusion: Eventually, the core of the cloud becomes so hot and dense that the hydrogen atoms begin to fuse together, forming helium. This process releases an immense amount of energy, which is what makes stars shine.