Scope

By default all subroutines (and functions) are public which means they can be called by code in ANY other code modules.
For clarity it is often good to prefix your subroutines with the word "Public"

Public Sub MySubroutine() 
End Sub 

Sub MySubroutine() 
End Sub 

Private procedures can only be called from within the SAME module.

Private Sub MySubroutine() 

End Sub 

Any subroutine that has a Private scope will not appear in the (Tools > Macro > Macros) dialog box.