The Sun is a ball of gas made mostly of two gasses: hydrogen and helium. Helium is what goes into balloons to make them float. The Sun is always working to change hydrogen to helium. The Sun makes the light that we see and the heat that we feel when we are outside during the day.
The Sun is one of many stars in our galaxy. Our sun is an average star. Some others stars are much bigger and others are much smaller. All of the other stars in the sky are much further away from us than the Sun. Their long distance away from us is the reason they look like tiny points of light in the night sky.
We measure the distance of stars from Earth in light years. A light year is the distance that light travels in one year. Since light travels at a speed of 186,000 miles/second (300,000 kilometers/second), a star that is one light year away is actually 5.8 trillion miles (9.5 trillion kilometers) from us! The Sun is only 8 light minutes away. That means that light from the Sun takes 8 minutes to get to earth. By comparison, if your friend turned on a very bright flashlight in California, you would see the light in about 1/60th of a second. Thats very quick! That is quicker than snapping your fingers! The closest star to us, other than the Sun, is Alpha Centauri, and it is 4 light years away. The most distant stars we can still see without a telescope are about 1000 light years away!
All the stars we see at night from Earth are also stars in our Milky Way Galaxy. There are over 100 billion stars in our Galaxy, but on an average dark night we can only see about 1000 to 1500 of them! Stars produce light and heat by changing hydrogen into helium, just like the Sun (remember, the Sun is a star, too!).