How can the required attribute in HTML be used effectively to ensure form fields are filled out without resetting already entered data?

To ensure form fields are filled out without resetting already entered data, the required attribute in HTML can be used effectively. This attribute specifies that an input field must be filled out before submitting the form. By adding the required attribute to the form fields, users will be prompted to fill out any empty fields without losing any data they have already entered. ```html <form method="post" action="submit.php"> <label for="name">Name:</label> <input type="text" id="name" name="name" required> <label for="email">Email:</label> <input type="email" id="email" name="email" required> <input type="submit" value="Submit"> </form> ```