<body>
<div class="limiter">
<div class="container-login100">
<div class="wrap-login100">
<div class="login100-pic js-tilt" data-tilt>
<img src="images/img-01.png" alt="IMG">
</div>
<form class="login100-form validate-form" method="POST">
<span class="login100-form-title">
Say
</span>
<div class="wrap-input100 validate-input" data-validate = "ID required">
<input class="input100" type="text" placeholder="Id" name="ID">
<span class="focus-input100"></span>
<span class="symbol-input100">
<i class="fa fa-envelope" aria-hidden="true"></i>
</span>
</div>
<div class="wrap-input100 validate-input" data-validate = "Mesage required">
<input class="input100" type="text" placeholder="Message" name="msg">
<span class="focus-input100"></span>
<span class="symbol-input100">
<i class="fa fa-lock" aria-hidden="true"></i>
</span>
</div>
<div class="container-login100-form-btn">
<button class="login100-form-btn">
Login
</button>
</div>
<div class="text-center p-t-12">
<span class="txt1">
Forgot
</span>
<a class="txt2" href="#">
Username / Password?
</a>
</div>
<div class="text-center p-t-136">
<a class="txt2" href="#">
Create your Account
<i class="fa fa-long-arrow-right m-l-5" aria-hidden="true"></i>
</a>
</div>
</form>
</div>
</div>
</div>
array(2) {
["id"]=>
string(1) "1"
["msg"]=>
string(18) "Сообщение"
}// Если данные не были получены, переменные будут содержать значение null.
$id = $_POST['id'] ?? null;
$msg = $_POST['msg'] ?? null;