HoldComplete[expr] shields expr completely from the standard Mathematica evaluation process, preventing even upvalues associated with expr from being used.

Show Stack Window toggles the display of the evaluation stack window on or off.

Unevaluated[expr] represents the unevaluated form of expr when it appears as the argument to a function.

Defer[expr] yields an object that displays as the unevaluated form of expr, but that is evaluated if it is explicitly given as Mathematica input.

Show Breakpoints Window toggles the Breakpoints window on or off.

HoldAllComplete is an attribute which specifies that all arguments to a function are not to be modified or looked at in any way in the process of evaluation.

Show Debugger Tools Window toggles the display of the Debugger Tools window on or off.

HoldAll is an attribute which specifies that all arguments to a function are to be maintained in an unevaluated form.

StackComplete[expr] evaluates expr with intermediate expressions in evaluation chains included on the stack.

StackBegin[expr] evaluates expr, starting a fresh evaluation stack.