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

While most built-in Mathematica functions follow the standard evaluation procedure, some important ones do not. For example, most of the Mathematica functions associated with ...

The following is the sequence of steps that Mathematica follows in evaluating an expression like h[e_1,e_2…]. Every time the expression changes, Mathematica effectively ...

Definitions such as f[x_]=x^2 specify values for functions. Sometimes, however, you need to specify general properties of functions, without necessarily giving explicit ...

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

SequenceHold is an attribute that specifies that Sequence objects appearing in the arguments of a function should not automatically be flattened out.

Evaluate[expr] causes expr to be evaluated even if it appears as the argument of a function whose attributes specify that it should be held unevaluated.

Hold[expr] maintains expr in an unevaluated form.

Attributes[symbol] gives the list of attributes for a symbol.

ValueQ[expr] gives True if a value has been defined for expr, and gives False otherwise.