A vector notation accent placing an arrow above a symbol to indicate vector quantities in physics and linear algebra.
Examples
Force vector in physics
\vec{F} = m\vec{a}
Vector addition in mechanics
\vec{F}_{net} = \vec{F}_1 + \vec{F}_2
Vector field notation
\vec{F}(x,y) = P(x,y)\hat{i} + Q(x,y)\hat{j}