What is the definition of "y-intercept"?

The y-intercept is the point in a function where the value of the x-coordinate is zero. By definition, a function has only one y-intercept. The x-intercept is the point in a function where the value of the y-coordinate is zero.

Using the slope intercept form of an equation, expressed as y = mx + b, the variable b is equal to the y-intercept, and the variable m is equal to the slope. When x is zero, the value of mx is also zero, resulting in y = b. When graphed, the y-intercept can be found at the point where the graph of the function crosses over the x-axis.