What are styles?
Most people are used to writing documents according to physical attributes. For example, you might specify the font family, font size, and weight (for example: Helvetica 12pt, bold).
Styles are logical attributes. We use styles every day. For example, there are two styles of computers: desktop and laptop. Each has its own distinctive set of properties. You never say “my computer is a low-weight, one-piece unit with an LCD screen attached to a rectangular casing containing the computing components and the keyboard". Instead, you would say that you have a laptop.
OpenOffice.org (OOo) styles are a way to do the same thing for your document. Using styles means that you could stop saying “font size 14pt, Times New Roman, bold, centered" and start saying “title" for describing that particular font usage. In other words, styles mean that you shift the emphasis from what the text looks like, to what the text is.