Option Explicit

When you use the Option Explicit statement, you must explicitly declare all variables using the Dim, Private, Public, or ReDim statements.
If you attempt to use an undeclared variable name, an error occurs.
VB Script in general doesn't need variable declaration. Without using Dim, a variable can be directly used for assigning. For ex - temp=1
However, such practice can always be error prone. Ex: If i want to use the same variable in some other statement and miss spell it, say tempe=temp+1
VB Script still considers "tempe" as valid. In this case if we use Option Explicit on top of our script and proceed, then application will not proceed unless until u declare each and every variable.
Hence you make sure that your variable is serving your purpose.