I have a php contact form. It is not working, I don't know why.
HTML CODE:
    <!-- Contact section -->
    <section class="contact" id="contact">
        <h2 class="heading">Contact <span>Me !</span></h2>
        <form action="contact.php">
            <div class="input-box">
                <input type="text" name="name" placeholder="Full Name">
                <input type="email" name="email" placeholder="Email Address">
            </div>
            <div class="input-box">
                <input type="number" name="number" placeholder="Mobile Number">
                <input type="text" name="subject" placeholder="Email Subject">
            </div>
            <textarea name="message" id="" cols="30" rows="10" placeholder="Your Message"></textarea>
            <input type="submit" value="Send Message" class="btn">
        </form>
    </section>
    <!-- Contact section end -->`
PHP CODE:
<?php
if(isset($_POST['submit'])){
    
    // Collect form data //
    $name = $_POST['name'];
    $email = $_POST['email'];
    $mobile = $_POST['number'];
    $subject = $_POST['subject'];
    $message = $_POST['message'];
    
    // My email //
    $to = "#mail@mail.com#";
    
    // Set email headers //
    $headers = "From: " . $name . " <" . $email . ">\r\n";
    $headers .= "Reply-To: " . $email . "\r\n";
    
    // Build email content //
    $email_content = "Name: " . $name . "\n";
    $email_content .= "Email: " . $email . "\n";
    $email_content .= "Mobile Number: " . $number . "\n";
    $email_content .= "Subject: " . $subject . "\n";
    $email_content .= "Message: " . $message . "\n";
    
    // Send email //
    mail($to, $subject, $email_content, $headers);
    header("Location: index.html");
}
?>
I try to make own contact form php fail on my webpage.
 
    