Rewrite the equation in exponential form. \[ \log _{x}(81)=y \]

Step 1 ：Rewrite the equation in exponential form. The given equation is \(\log _{x}(81)=y\). To convert it to exponential form, we need to remember that the base of the logarithm becomes the base of the exponent, the result of the logarithm becomes the power, and the argument of the logarithm becomes the result of the exponentiation.

Step 2 ：The exponential form of the given equation is \(\boxed{x^y = 81}\).