Let’s have a little lesson in microeconomics, shall we? The graph above is an illustration of the basic supply and demand curves shown in every Econ 101 text. These graphs illustrate that as the price of something increases people tend to buy less of it, suppliers make more of it, and there’s an “equilibrium price” where the lines cross, i.e. supply and demand are equal. Simple enough.
This graph has a little difference. It adds an additional demand curve to illustrate the effect of an increase in demand on prices, supply, and the equilibrium price. As you probably have already predicted, with a demand shift that increases demand the supply and equilibrium price both increase.
There’s one more little difference. The blue vertical bar indicates a fixed supply. As you could probably guess when supply is fixed and there is a shift that increases demand, it will increase the equilibrium price.
One last little observation. What happens if the increase in the equilibrium price in response to a demand shift and a fixed supply itself results in another demand shift that increases demand? Then you have a positive feedback loop which will continue stopped by some exogenous factor.