Client-side scripting, as the name implies, is script code that is executed on the client. This is commonly used for purposes of form validation. For example, if you create a form that contains a text box for the user to enter his or her age, you don't want to let the user enter values like "Bob" or "53213". One way to prevent this is to let the user submit the form, even with erroneous values, and check whether or not the values the user entered were valid using ASP. This is referred to as server-side form validation. Client-side form validation, on the other hand, checks to make sure the values entered into the form are valid before the form is submitted to the server.