What is a style?
A style is a group of formats identified by a label (style name). Choose the formats to apply to the style and give that group of formats a unique name. Once this is done, apply the whole group of formats in one step just by positioning the cursor in the paragraph to be formatted, and then selecting the style name from the Style box on the Home tab.
As a short cut, new styles can be created based upon existing styles. Once this is done, changes to a parent style automatically apply to any "children" styles based on it. For more information, see About Cascading Styles.