From Tutorialized.com – Latest Tutorial Listings For CSS –CSS3 Selector Principals #3 Class:
When you have a group of elements that you’d like to apply styles to, or rather, have an element you’d like to inherit a certain set of style rules, the class selector will likely be your weapon of choice. While it’s possible to use multiple selectors on a style definition, the preferred method is that you create a style class, which can then be applied to any element within that class.