Dictionary.net

An argument passing convention where theaddress of an argument variable is passed to a function orprocedure, as opposed to passing the value of the argumentexpression. Execution of the function or procedure may haveside-effects on the actual argument as seen by the caller.The C language's "&" (address of) and "*" (dereference)operators allow the programmer to code explicitcall-by-reference. Other languages provide special syntax todeclare reference arguments (e.g. ALGOL 60).See also call-by-name, call-by-value,call-by-value-result.