⟹
Symbol  Format  Data 

⟹  Code Point 
U+27F9 
TeX 
\Longrightarrow 

SVG 
In math, the long right double arrow is used to denote logical implication. Typically it is used in an expression like this:
In plain language, this means that if is true, then must necessarily be true.
Long right arrow symbol.
Long left double arrow symbol.
The if and only if symbol is used as a logical statement.