align of box

Question

what is code to align box in center of the screen?
where ot use?

Answer 1

margin: 0px auto;

Answer 2

use style= "vertical-align:middle;"

Answer 3

perhaps can use 1. relative position or 2. float with some measurements.

Answer 4

use CSS make it margin 0px auto to get it to the centre of the div you want to display it on