1. The problem asks what kind of numbers the y-coordinates of an exponential function take. 2. An exponential function is generally defined as $$y = a^x$$ where $$a > 0$$ and $$a \neq 1$$. 3. For any real input $$x$$, the output $$y = a^x$$ is always positive but can be any positive real number depending on $$x$$ and $$a$$. 4. This means the y-coordinates are not restricted to integers, natural numbers, whole numbers, or rational numbers alone. 5. Since $$a^x$$ can be irrational for many $$x$$ values (for example, $$2^{\sqrt{2}}$$), the y-coordinates include all positive real numbers. 6. Therefore, the y-coordinates of an exponential function are positive real numbers.