Validation is pretty much necessary in almost all kind of applications. The simple fact is that humans are prone to make mistakes while entering data. In order to build a fully fledged application which is free from errors and not susceptable to crashes we should pay attention to input validation. Input validation is the process of making sure that the user provides the accurate type of data because “prevention is better than cure”. If an application requires certain specific data and we feed another type of data then definitely the result is an error. So care must be taken to enter data in a particular format. This can be better explained with the help of an example.