Vertical Line Test

The vertical line test can be used to determine if a curve is the graph of a function. The vertical line test determines if for every value of x there is only one output y corresponding to it. The picture below shows the graph of the function and the line . By adjusting the values of , check that passes the vertical line test for , i.e. for every value of there is only one output corresponding to it.

Graph of h(x)

What about the curve below, does it pass vertical line test? Does this curve represent a function? Explain your answer.
Can you think of what features a curve must have to be the graph of a function? Perhaps contrast the two graphs shown above.