ContourPlot

ContourPlot[f, {x, xmin, xmax}, {y, ymin, ymax}] generates a contour plot of f as a function of x and y.

Examples

Contour plot of a function:

ContourPlot[Sin[x] Sin[y], {x, -Pi, Pi}, {y, -Pi, Pi}]

Plot a specific contour:

ContourPlot[x^2 + y^2 == 1, {x, -2, 2}, {y, -2, 2}]

Please visit the official Wolfram Language Reference for more details.