Any VB.net program has On mode of option explicit by default. If program has Option explicit On statement than it requires all variables have proper deceleration otherwise it gives compile time error now we talk about another mode Off - if we are using variables without declaration than vb.net create variable declaration automatically and program does not give an error

We can take an example for better understanding:

Option Explicit On

Public Class Form1
Private Sub OptionExplicit()

TempString = "Hello"

MessageBox.Show(TempString)

End Sub

End Class

Above program gives an error ‘Name TempString is not declared'

Option Explicit Off

Public Class Form1
Private Sub OptionExplicit()
 TempString = "Hello"
MessageBox.Show(TempString)
 End Sub

End Class

Above program run continue with out error