As you learn more, it will become obvious that terroir is a French term. And further, it will become clear that there is no true translation into the English language. The best description for terroir, that I can give, is the all encompassing "sense of place" that a wine has. It is that special mix of soil, climate, aspect of the vineyard (topography), and everything else that can affect the final grape product. All of these are unique to each vine, and remain the same every year. This sense of place contributes to the final wine produced, regardless of what is done during the winemaking process.
Now, going back to the components of terroir, I mentioned, soil, climate, aspect, etc. As "terroir" suggests, it is tied to the soil. The soil texture, drainage, and the make up of the elements all affect the grapevine, and ultimately the grape. Limestone, granite, chalk, slate and clay are all associated with some of the great wines of the Old World. The soil can retain heat, reflect heat, drain excess moisture, or retain it. The choice of soil for planting affects the total vine.
As you can tell, the word "terroir" implies all things that are natural to the place.
I know where I stand on this, and I am a believer in terroir. I can taste subtle nuances from wines grown within the same growing region, but in different areas of that region. The best example would be Paso Robles (east versus west) or Napa versus Sonoma. Even though they are close to each other, they are all different.
So, are you a "terroirist"? Do you seek that sense of place in your wines?