# What does an upside down delta mean - covariant vectors? [duplicate]

I was scrolling through a wiki article on terminal velocity when I spotted an upside down delta. What does this symbol mean? How is it applied in other contexts?

EDIT: If possible could someone expand upon "a covariant vector made of space derivatives?" I sort of understand how a vector can be made up of partial derivatives, but what does covariant mean?

• Does this answer your question? $\nabla$, $\cdot \nabla$, $\nabla \cdot$, $\nabla^2$ - What do they do?
– Amit
Jun 3, 2023 at 17:34
• Yes @Amit this looks like it answers my question thoroughly! Jun 3, 2023 at 17:57
• Re: Edit -- This question is now closed as a duplicate, and in general posts should contain one question without being later edited to widen their scope. You may of course post a new question -- but I strongly suggest that you first carry out a search to see if a similar question to your new one also exists. For more general guidance on how to ask a good question click here
– Amit
Jun 3, 2023 at 18:19

Edit: $$\vec\nabla f= \begin{pmatrix} \dfrac{\partial f}{\partial x}\\ \dfrac{\partial f}{\partial y}\\ \dfrac{\partial f}{\partial z} \end {pmatrix}$$