CSS shortland is a technique of writing mulitple declarations and values in a single line of CSS code. The advantages of using shorthand is to primarily reduce the CSS file size, but there are other benefits. A bloated and disorganised stylesheet can be hard to debug if you encounter problems, especially if you wrote it and another unfortunate colleage has to fix it while your away sunning it in some hot climate.

Read more: http://www.thefloatingfrog.co.uk/web-design/10-css-shorthand-techniques-youll-use-everyday/