<title>Bootstrap 4 Form with Help Text</title>
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/css/bootstrap.min.css" crossorigin="anonymous">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.1/dist/umd/popper.min.js" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/js/bootstrap.min.js" crossorigin="anonymous"></script>
<label for="password">Password</label>
<input type="password" class="form-control" placeholder="Your password">
<small class="form-text text-muted">
Password must be 8 to 20 characters long, contain letters, numbers, special characters, and must not contain spaces.