Answers for "viewport what is it"

viewport

// viewport for Responsive Design
<meta name="viewport" content="width=device-width, initial-scale=1.0">

viewport

<!-- Responsive // Viewport -->
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">