• Alias: dd. • Compound operator with built-in evaluation rules. • can only be interpreted by default when it appears with or other integral operators. • fx is by default interpreted as Integrate[f,x]. • \[DifferentialD] is also used in TraditionalForm to indicate total derivatives. • See also: \[PartialD] , \[CapitalDifferentialD] , \[Delta] .
\[DifferentialD]
dd
can only be interpreted by default when it appears with 
or other integral operators. 
f 
x is by default interpreted as Integrate[f, x]. 