In this lesson, we’ve explored form validation from many angles. Let’s review what we covered:

• Modern websites require a lot of information from their users and they collect a lot of this information through HTML forms.
• It’s essential to validate the data submitted through forms to keep websites secure and to make sure they function correctly.
• Regular expressions are sequences of characters that define patterns to look for in text. They are an important tool used in validating input.
• Modern HTML comes with useful built-in methods for form validation.
• Custom and complicated client-side validation can be accomplished with JavaScript.
• Asynchronous requests to the server can perform back-end validations before a form has been submitted.
• A final back-end validation of all data is required to ensure an application’s security and sanitize all data.