NHoldAll is an attribute which specifies that none of the arguments to a function should be affected by N.

Definition[symbol] prints as the definitions given for a symbol.

SetAttributes[s, attr] adds attr to the list of attributes of the symbol s.

Any Mathematica symbol can have both a variety of types of values, and a variety of independently settable attributes that define overall aspects of its behavior.

Mathematica normally takes any expression it is given, and evaluates it as far as possible. But built into the Mathematica language is a collection of flexible primitives ...

At the core of Mathematica is the foundational idea that everything —data, programs, formulas, graphics, documents—can be represented as symbolic expressions. And it is this ...

HoldRest is an attribute which specifies that all but the first argument to a function are to be maintained in an unevaluated form.

CheckAbort[expr, failexpr] evaluates expr, returning failexpr if an abort occurs.

HoldPattern[expr] is equivalent to expr for pattern matching, but maintains expr in an unevaluated form.

FullDefinition[symbol] prints as the definitions given for symbol, and all symbols on which these depend.