It is a shorthand for the vector:
<math>\begin{pmatrix} {\partial / \partial x} \\ {\partial / \partial y} \\ {\partial / \partial z} \end{pmatrix}</math>
The symbol was introduced by William Rowan Hamilton, and is sometimes called nabla, after the ancient Hebrew instrument which the shape resembles.
The operator can be applied to scalar fields (<math>\phi</math>) or vector fields (<math>\mathbf{F}</math>), to give:
See also:
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