To find the \( y \)-intercept of the parabola given by the equation \( y = x^2 \), we need to evaluate the function when \( x = 0 \).
Substituting \( x = 0 \) into the equation:
\[ y = (0)^2 = 0 \]
Thus, the \( y \)-intercept is \( 0 \).
So, the \( y \)-intercept of the parabola is:
\[ \boxed{0} \]