Option Definition

Syntax:
Option Explicit
-or-
Option Private Module
Group: Declaration
Description:
Form 1: Require all variables to be declared prior to use. Variables are declared using Dim, Private, Public or Static.

Form 2: Public symbols defined by the module are only accessible from the same project.
Example:

Option Explicit

Sub Main
Dim A
A = 1
B = 2 ' B has not been declared
End Sub