Infix operator with built-in evaluation rules.
x y is by default interpreted as Implies[x, y].
x y z groups as x (y z).
Not the same as \[DoubleRightArrow].
\[DoubleRightArrow] is extensible; \[Implies] is not.
See The Mathematica Book: Section 1.10.4, Section 3.10.1, Section 3.10.4 and Section 3.10.4.
See also: \[RoundImplies] , \[SuchThat] , \[RightArrow] , \[Rule] .