Britannica says $a^k$ is the power; Wikipedia says that the power is $k$. Which one is it? Did someone make a mistake?
Just as a repeated sum $a + a + \cdots + a$ of $k$ summands is written $ka$, so a repeated product $a × a × \cdots × a$ of $k$ factors is written $a^k$. The number $k$ is called the exponent, and $a$ the base of the power $a^k$.
In mathematics, exponentiation is an operation involving two numbers, the base and the exponent or power. Exponentiation is written as $b^n$, where $b$ is the base and $n$ is the power; this is pronounced as "$b$ (raised) to the (power of) $n$".
(Bold added in both quoted texts)
I see people insisting that $k$ is a power and $a^k$ is also a power at the same time. While we are at it, why not call $a$ a power too? What do you say?