As being the central point of our solar system, the sun's gravity is the power that keeps all together. Compared to the size of other stars in the galaxy or the whole universe, our home star is just a medium sized. But nevertheless this doesn't means it is small. For dominating the solar system with its gravity and so make the orbits of the planets possible a huge mass is necessary. Imagine Jupiter as a so called Gas Giant, its mass is 318 times the mass of earth but only a 1048th part of the mass of the sun. Hence the sun owns 99,86% of the whole mass of the solar system.
The age of our sun, therefore timespan since the creation of our star system, is calculated to about 4.6 billion years. Calculations, regarding the current mass of the sun and so the remaining fuel for the fusion processes that take place inside the sun, show that the suns active live will last until the age of 12.5 billion years. We have summarised some more information about the central star of our solar system.
The sun mainly consists of the elements hydrogen (75%) and helium (23%). Due to the large mass the pressure in the middle of the sun is immensely high round about 200 billion times the average pressure of earth's atmosphere. No other place in the solar system is of this pressure. Big pressure causes big temperatures a so the temperature in the core of the sun is about 15.6 million°C. This environment causes the fusion of hydrogen and helium. This process releases a high amount of energy and is the cause why our sun illuminates that bright and produces so much heat. Without that live on earth wouldn't be possible at all.
In about 8 billion years from now, the fusion process in the core of the sun will stop. This is because the fuel for the fusion is used up. Because of that the sun will rise to a big red star, destroying the planets Mercury and Venus and melt the Earth's surface. Then sun will shrink to a little white dwarf and stay like this forever.