To summarize, according to the W3C, a selector is a chain of one or more simple selectors separated by combinators. Combinators are: whitespace, ">", and "+". Whitespace may appear between a combinator and the simple selectors around it. Curabitur venenatis sollicitudin cursus. Duis rutrum lorem ac sem laoreet consectetur. Proin eget fringilla dui. Pellentesque varius sem ac neque commodo vel molestie nisi hendrerit.
The W3C also states that one pseudo-element may be appended to the last simple selector in a chain. Pellentesque eros turpis, feugiat sed pellentesque in, ultrices at enim. Nullam et sapien tortor. Donec tincidunt mattis placerat. Pellentesque eget enim eu urna adipiscing varius eu vitae urna. Vivamus id pharetra erat.
Much of the rest this document will use text called Lorem Ipsum, rather than meaningful information. Morbi dapibus tellus dolor, at venenatis risus. Nam at pharetra odio. Aliquam erat volutpat. Ut sed sem ipsum, vitae congue est. Sed dignissim lorem quis lectus molestie sollicitudin. Ut quis justo ac mi vestibulum laoreet.
Lorem Ipsum is dummy text that has been used by the printing and typesetting industry ever since the 1500s. It has its roots in a piece of classical Latin literature from 45 BC, de Finibus Bonorum et Malorum by Cicero. Ut tempor arcu sit amet nisl interdum ac tempus augue posuere. Fusce at metus ut lectus laoreet facilisis at at enim. Pellentesque varius, massa et tempus imperdiet, arcuSed sodales vestibulum magna sit amet ultricies.
There is a Lorem Ipsum generator at http://www.lipsum.com/ that produces realistic-looking text. liquam vel lacus mauris. Maecenas accumsan accumsan placerat. Mauris eu sapien lacus, sed fermentum urna.