In html 3, there's a “center” tag for centering:
<center><p>hi</p></center>
In html 4 transitional, you can use “align="center"”.
Here's how to do it with CSS.
Blow is a centered block done using CSS.
<div style="margin-left: auto; margin-right: auto; text-align:center;">Hi</div>
In summary, use “text-align:center” to center a text inside a tag. Use “margin-left:auto; margin-right:auto;” to center a block level tag.