Modular programming is a programming technique in which a program is divided into many small logical, manageable and functional parts.

Any four advantages of modular programming are listed below:
1) The same procedure can be used more than once without rewriting it. So, it reduces the length of the program.
2) Individual procedure can be written independently so;it is suitable for a teamwork.
3) The debugging of the program becomes easier and faster.
4) The procedure can be tested and...

The small, logical and functional part of the program is known as procedure or module.

The types of procedures are listed below:
1) SUB procedure.
2) FUNCTION procedure.

The constants or variables included in the parenthesis of the calling statement are known as argument. It is also known as actual parameter.

The variables included in the parenthesis of the procedure which accepts constants or variables passed to them from the calling module is known as parameter. It is also known as formal parameter.

Argument passing by reference method means the method of passing arguments to the procedure in which the addresses of the variables are passed with the parameters with the same memory addresses.

Variable is a value that can change, depending on conditions or on information passed to the program.

A variable which is defined in a module and is not accessible to any other modules is known as local variable.

A variable which is defined in main module and can be accessed from any procedure of the program is known as global variable.

The CALL is statement is used to call a SUB procedure.

[CALL] name [([argumentlist])]
where,
‘name’ is the name of the SUB procedure to be called.
‘argumentlist’ is the list of constants or variables that are passed to the SUB procedure. The list of variables or constants is separated with commas.