Plotting X = y^2 is plotted as a vertical parabola. Why?

My question is simple, but I have had a hard time finding the answer in documentation.
I am new to Mathematica.
Y = X^2 is a vertical parabola when plotted.
When I plot X = Y^2 I get a vertical parabola.

this would usually be a horizontal or flat Parabola? Why am I getting a vertical parabola: what am I missing?

Thank you,
Lynn J Robbins

A good place to start would be the documentation for Plot.

Hi Lynn,

it depends a bit on what you are plotting. If you use Plot then, as expected both functions give standard “vertical” parabolas. When you try to plot x=y^2 like that that would just be renaming the variables. If however you use ContourPlot

ContourPlot[{y == x^2, x == y^2}, {x, -2, 2}, {y, -2, 2}]

you get

which appears to be what you want. ContourPlot, if used like this, plots the sets of points for which the equations hold. Note that the yellow/gold curve does not represent a function because for all x>0 it gives two solutions.

Best wishes,

Marco

ParametricPlot is also a possibility:

ParametricPlot[{y^2, y}, {y, -2, 2}]