 <p>You should perform validations at server side as well as client side.Client side validations increase interactivity of your applications.In other words make your application more user friendly.However client side validations may have their shortcomings , if your user disables javascript , then he could very well enter non sense data values and send them to your server.You dont want this to happen.For that purpose you need to perform server side validations.Server side validation controls filter the input and make sure proper data is entered.There are good validation controls Asp.Net offers.You could very well utilize them. I recommend you to use both client as well as server side validation for a blend of interactivity and protection. Thanks</p>