What are the key steps involved in creating a form for users to input and save messages in a PHP application?

To create a form for users to input and save messages in a PHP application, you will need to first create the HTML form with appropriate input fields. Then, you will need to write PHP code to handle the form submission, validate the input data, and save the messages to a database or file.

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $message = $_POST['message'];

    // Validate the input data here

    // Save the message to a database or file
}
?>

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
    <label for="message">Message:</label><br>
    <textarea id="message" name="message"></textarea><br>
    <input type="submit" value="Save">
</form>