Adding Form Validation

We have one last major feature to add to our form, validation. Form validation is a set of checks that evaluates users' provided value.

There are 2 types of validation:

1. Client-side validation
   1. Ensure required fields have values.
   2. Prevent invalid values.
   3. Provide timely feedback.
2. Server-side validation
   1. Mirroring client-side validation.
   2. Complex validation rules.
   3. Validate against values from a database or API

Today, we will learn 2 examples of delivering message validation.