A two-dimensional electron gas (2DEG) is a gas of electrons free to move in two dimensions, but tightly confined in the third.
In mathematics, it seems that there could be $n$ dimensions, but how's it on the "real world"? I thought that such $n$-dimensional objects on the real world could exist on the absence or presence of a specific dimension, but at least in this wikipedia article, it seems that this object have the third dimension - at least I conceive "confined" as something different of "abscence". Can you clarify this to me?
I am open to both answers and references on this topic, I just hope that asking both is not being too broad.