Several methods of passing parameters between calling program and subroutine are used:

1. Call by Reference: The address of the parameter is passed. The storage in the calling program is used (and possibly modified). Used by Fortran, Pascal for var parameters, C for arrays.

2. Call by Value: The value of the parameter is copied into the subroutine's memory. Modifications have no effect as seen by caller. Expensive for large data. Used in Pascal, C for basic types.

3. Call by Value - Result: The value of the parameter is copied into the subroutine, and the result is copied back upon exit.

4. Call by Name: The effect is that of a textual substitution or macro-expansion of the subroutine into the caller's environment. Trouble-prone, hard to implement, slow. Used in Algol.

5. Call by Pointer: A pointer to the parameter value is passed. Used in Lisp.

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