Validations always plays a vital role in making the user comfortable in filling the forms with correct details.
Using Jquery we can validate the forms before sending to a server which minimizes the server load. This can be one using a jquery plugin called validate.js ,
I have included it with enough examples on this page. For eg the first input checks for a email is input or not and also it should be required.
It checks the format of firstname.lastname@example.org