Soil is a mixture of minerals, living things, water, air, etc. Soil is full of living organisms which create a rich environment where plants (which are also alive) can grow. You can find worms and insects in soil, also fungi, and many bugs. Some of these living things can not be seen without a microscope, but they are there and they are responsible for the well growing of plants.

Depending on the composition of the soil, different plants can grow. There are different kinds of soil, depending on how they are formed. You may have noticed that some soils are almost black, some are brown, etc. The plants that grow on a certain soil are the ones that need the specific ingredients on that soil.

Here is a nice link where you can learn more about soil.