What are priVATe functions in QTP? How they can be called from the function library?

Private funtion is a type of function which other functions can call within a script i.e. is only accessible to functions inside the script, not accessible outside the script. If any private function...Private functions means which are specific to your application, ex: Login to your app, you can call them in 2 ways
1. By using the statement Executefile "c:fucntions.vbs"
2. By adding ur function library at the "Test Settings->Resources->Libraries"