Gravity has this quality of pulling things down... Do you feel it!?
If you weren't so alive and muscular, your body would eventually be drawn to the soil and... become a part of it, just like everything else that is not alive anymore. Dead things decay and are broken down by small animals (and not so small at times) and microorganisms into small molecules and base elements (which is crazy to even think about!). Plants can then absorb that as nutrients, grow, and eventually be consumed by some living organism either before or after it is dead... and start over!
Soil is the interface that enables this cycle of renewal, of turning death into life.
In this way, soil is like a digestive system. The Earth's digestive system, you could say. The process of digestion is aided by microorganisms, just like in your guts. Nutrients are taken up by roots, much like veins, and then distributed to where they are needed in new forms. I just skipped so many important steps and processes but I hope this illustration serves its purpose: to illustrate!
Now let's get a little more specific. What is soil really made of?
The short and accurate answer would be: mineral particles (silicates, quartz etc), organic matter, living organisms, and water. These are your main ingredients.
The sizes and types of mineral particles will determine the texture of your soil. As you see in the diagram below, soils can be clay, silt or sand dominant, giving soil different physical and electrochemical properties, as well as greatly affecting how water behaves in it and what root systems (plants) are compatible with it. This is one often overemphasized, but yet very important dimension of soil
To finish off with a "to be continued" type of note:
The amount and quality of organic matter, living organisms and water in your soil will determine its overall quality and fertility. Where it gets tricky: all these factors (including texture) are always affecting each other along with some other factors not yet mentioned...
To leave you with a tip in case you are trying to grow something and can't wait until the next post: organic matter (as compost, manure, plant waste etc.), lots of living roots, just enough water and fluffy love will get you growing most things.
Talk to you soon!