What could be simpler and faster than using CSS to set up your website? Using CSS shorthand to set up your website. While not all browsers support all of CSS shorthand's features, enough of them are supported to allow you to write tighter code, and create a website that loads more quickly.
Margin properties set the size of the margin between the outside of an element’s border and surrounding page elements. Let’s list some examples for proper understanding:
h2 {
margin: 5px;
}
h2 {
margin: 5px 20px;
}
h2 {
margin: 1em 2em 4em;
}
h2 {
margin: 5px 20px 5px 20px;
}
In the first example, all of the margins for the <h2> element are set to 5px. In the case where only one value is specified, it will be applied to all sides of the element. In the second example, where only two values have been specified, CSS interprets the first as being the value for the horizontal margins, that is, those at the top and bottom of the element. The second value defines the right and left margin sizes for the element.
In the third example, where three values have been defined, the first value is set to "margin-top," the second is set to "margin-right" and the third is set to "margin-bottom," respectively.
When four margin values are defined for the element, they’re automatically applied to the borders, moving around the element in a clockwise direction, that is top, right, bottom and left, respectively.
Let’s see another interesting shorthand property, which consists of using padding.
Style Sheets 
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HTML5 Boilerplate Introduction
