Step 1: The function \( y = \tan^{-1} x \) is the inverse of the tangent function. By the definition of the inverse tangent (or arctangent), it returns the angle \( y \) such that:
\[
\tan y = x.
\]
Step 2: The range of the arctangent function \( \tan^{-1} x \) is restricted to \( -\frac{\pi}{2} \leq y \leq \frac{\pi}{2} \). This is because the tangent function is periodic, and the principal value of the inverse tangent is chosen to lie within this interval to ensure it is a one-to-one function.
Thus, we conclude:
\[
-\frac{\pi}{2} \leq y \leq \frac{\pi}{2}.
\]