The old way:

<p>
Demo paragraph text. Demo paragraph text.

<p align="center">
Demo paragraph text. Demo paragraph text.

<p align="justify">
Demo paragraph text. Demo paragraph text.

<p align="left">
Demo paragraph text. Demo paragraph text.

<p align="right">
Demo paragraph text. Demo paragraph text.

The new HTML5 way:

Aligns text to the center.

Justifies text.

Normal left alignment. No need to specify.

Aligns text to the right.