One of the defining properties of a [[Vector]]. What we refer to as the 'magnitude' of a vector is typically the [[Norm|Vector Norm]] / [[LP Norm]], $\ell_{2}$. To get the magnitude of a vector, you can treat the vector's Cartesian coordinates as the $x$ and $y$ of a triangle. $\huge||\vec{v}|| = \sqrt{ \vec{v}_{0}^{2} + \vec{v}_{1}^{2} + \cdots }$