x <= y or x y yields True if x is determined to be less than or equal to y.
yields True if the form a non-decreasing sequence.
x y can be entered as x <= y or x \[LessEqual] y.
LessEqual gives True or False when its arguments are real numbers.
LessEqual does some simplification when its arguments are not numbers.
For exact numeric quantities, LessEqual internally uses numerical approximations to establish numerical ordering. This process can be affected by the setting of the global variable $MaxExtraPrecision.
In StandardForm, LessEqual is printed using .
x y, entered as x </ y or x \[LessSlantEqual] y, can be used on input as an alternative to x y.
See The Mathematica Book: Section 1.5.6.
See also: Less, GreaterEqual, Element.