In the real world, it's not a case of either server-side or client-side validation. We can have both types of validation at the same time. In fact, it is recommended to validate the data at both ends to avoid unnecessary processing.
The preceding figure shows the validation is being performed at both the client-side and the server-side. If the data is not entered into the required field, we can catch that issue at the client-side itself. There is no need to send the data to the server to finally find out that there is no data entered. Once all the required data is entered, the data is sent back to the server to validate the entered data based on some business logic. If the validation fails, the form data is sent again to the browser with the error message so that the user can send the data again.
We have covered enough theory about the need for validation and the types of validations typically used in the application. Let us get our hands dirty by adding...
