When you look at the sky, you can see many 'stars'. There are billions of stars in the solar system, and one of them is the sun.

You need to understand the simple stages in the development of a star:

1. The star begins as a 'nebula'. At the start of a star's life cycle, a nebula will be formed. This is simply a cloud of gas, rock and dust. When this cloud is drawn together by gravity, it is called a protostar.

2. Fusion reactions occur within the star. As the protostar forms, its core will undergo fusion reactions. Gravity is the attractive force that causes these fusion reactions.

The Sun is a big star at the centre of our Solar System. The Sun was formed through this same process. It started as a nebula, which was pulled together by gravitational attraction to form a protostar