index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Form Validation</title>
    <link rel="stylesheet" href="css/style.css">
</head>

<body>
    <form class="form" id="form">

        <div class="segment">
            <h1>Sign up</h1>
        </div>

        <label>
            <input class="username form-control" id="username" type="text" placeholder="Enter Username" />
            <small>Error Message</small>
        </label>

        <label>
            <input class="email form-control" id="email" type="text" placeholder="Email Address" />
            <small>Error Message</small>
        </label>

        <label>
            <input class="password form-control" id="password" type="password" placeholder="Password" />
            <small>Error Message</small>
        </label>

        <label>
            <input class="password2 form-control" id="confirmPassword" type="password" placeholder="Confirm Password" />
            <small>Error Message</small>
        </label>

        <button id="btn" class="red" type="submit"> Submit </button>

    </form>

    <script src="js/script.js"></script>
</body>

</html>