A Sub is a procedure that performs a specific task but does not return a specific value.

Sub ProcedureName ([argument_list])
    [statements]
End Sub

If no access modifier is specified, a procedure is Public by default.

A Function is a procedure that is given data and returns a value, ideally without global or module-scope side-effects.

Function ProcedureName ([argument_list]) [As ReturnType]
    [statements]
End Function

A Property is a procedure that encapsulates module data. A property can have up to 3 accessors: Get to return a value or object reference, Let to assign a value, and/or Set to assign an object reference.

Property Get|Let|Set PropertyName([argument_list]) [As ReturnType]
    [statements]
End Property

Properties are usually used in class modules (although they are allowed in standard modules as well), exposing accessor to data that is otherwise inaccessible to the calling code. A property that only exposes a Get accessor is "read-only"; a property that would only expose a Let and/or Set accessor is "write-only". Write-only properties are not considered a good programming practice - if the client code can write a value, it should be able to read it back. Consider implementing a Sub procedure instead of making a write-only property.

Returning a value

A Function or Property Get procedure can (and should!) return a value to its caller. This is done by assigning the identifier of the procedure:

Property Get Foo() As Integer
    Foo = 42
End Property

As stated above Functions are smaller procedures that contain small pieces of code which may be repetitive inside a Procedure.

Functions are used to reduce redundancy in code.

Similar to a Procedure, A function can be declared with or without an arguments list.

Function is declared as a return type, as all functions return a value. The Name and the Return Variable of a function are the Same.

 Function check_even(i as integer) as boolean
 if (i mod  2) = 0 then
 check_even = True
 else
 check_even=False
 end if
 end Function

 Function greet() as String
 greet= "Hello Coder!"
 end Function

The Function can be called in various ways inside a function. Since a Function declared with a return type is basically a variable. it is used similar to a variable.

Functional Calls:

   call greet() 'Similar to a Procedural call just allows the Procedure to use the
                 'variable greet 
    string_1=greet() 'The Return value of the function is used for variable
                     'assignment

Further the function can also be used as conditions for if and other conditional statements.

     for i = 1 to 10
      if check_even(i) then
      msgbox i & " is Even"
      else
      msgbox i & " is Odd"
      end if
      next i

Further more Functions can have modifiers such as By ref and By val for their arguments.