Solar System Diagram is one of the education and knowledge to mainly explain you about the order of our planets from the sun till the Neptune.
Do you know the place we are living in? By that means not our house, not our states either, but our planet which is Earth. Do you know that there are other planets just like Earth in the outer space? Yes exactly, there are several planets beside our living planet which is the Earth on the space. And they are orderly going around the Sun and orbiting. These well ordered orbit cycle is called solar system.
We have Mercury which is the nearest planet from the Sun followed by Venus and then our Earth. After that we have Mars and then Jupiter which is the biggest one among the planets. And Saturn, a planet which has ring on it. And till the end which is furthest one, Pluto. Check the diagrams below for the detail!