How to align a text inside a <div> element horizontally? : <p>How to align the text inside a div centrally vertically?</p>

<p>I have a div element inside my html page where and the height of the div is the screen size and the text inside that div need to be at the center. I have used text-align : center property to align it horizontally but i need to do that horizontally as well.</p>
