Why using $v^T \cdot u\text{ instead of simply } v \cdot u$?

Question

I know they are equivalent, but why and when should we prefer using $v^T \cdot u$ instead of simply $v \cdot u$, when $v$ and $u$ are vectors of $\mathbb{R}^m$, for example?

Answer 1

It tells you things like $(Au)\cdot v = u \cdot (A^Tv)$