jQuery Validation is a plugin that simplifies client-side form validation by providing built-in methods to check user input against common rules like required fields, email formats, and number ranges. Developers use it to catch form errors before submission, improve user experience with instant feedback, and reduce unnecessary server requests. It integrates directly with jQuery and HTML form elements, making it straightforward to add validation to existing forms without writing custom validation logic.

jzaefferer, staabm, bytestream