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  • Hold[ expr ] maintains expr in an unevaluated form.
  • Hold has attribute HoldAll, and performs no operation on its arguments.
  • Example: Hold[1+1].
  • Hold is removed by ReleaseHold.
  • Hold[ , , ... ] maintains a sequence of unevaluated expressions to which a function can be applied using Apply.
  • Even though expr itself is not evaluated, Hold[ expr ] may still evaluate if expr is of the form f [ args ], and upvalues for f have been defined.
  • See the Mathematica book: Section 2.5.5.
  • See also: HoldPattern, HoldForm, HoldComplete, Unevaluated, HoldAll, Symbol.

    Further Examples

    If you are in the form of an expression before it is evaluated, wrap Hold around the expression.