A very informative article about the CSS Reset design practice which resets the default margins/paddings that a browser applies to elements. Web Browsers most of the time applied a bit of styling to certain elements even if you are not using any stylesheets at all. You can see it in action when you create a <a> element. Most of the browsers render it as a blue, underlined text. But by resetting this behavior, you can view what a certain element would look like with no style applied to it at all.
Resetting Your Styles with CSS Reset