Mathematics Knowledge Question on Y-Intercept

What is the y-intercept of the line y = x?

In working as an ASVAB tutor, one of the topics I review for Mathematics Knowledge is angles and slope.  In reviewing angles and slope, I also talk about the slope of a line and the y-intercept of a line. It is important to be able to find the slope and y-intercept of a line.  Slope is the steepness of a line.  The y-intercept is the point where a line crosses the y-axis.  Do you know how to identify the slope of this line y = x?   I will present the answer and explanation tomorrow.