CSS - the Selector syntax

Pattern	Meaning	Described in section	level
*	any element	Universal selector	2
E	an element of type E	Type selector	1
E[foo]	an E element with a "foo" attribute	Attribute selectors	2
E[foo="bar"]	an E element whose "foo" attribute value is exactly equal to "bar"	Attribute selectors	2
E[foo~="bar"]	an E element whose "foo" attribute value is a list of whitespace-separated values, one of which is exactly equal to "bar"	Attribute selectors	2
E[foo^="bar"]	an E element whose "foo" attribute value begins exactly with the string "bar"	Attribute selectors	3
E[foo$="bar"]	an E element whose "foo" attribute value ends exactly with the string "bar"	Attribute selectors	3
E[foo*="bar"]	an E element whose "foo" attribute value contains the substring "bar"	Attribute selectors	3
E[foo|="en"]	an E element whose "foo" attribute has a hyphen-separated list of values beginning (from the left) with "en"	Attribute selectors	2
E:root	an E element, root of the document	Structural pseudo-classes	3
E:nth-child(n)	an E element, the n-th child of its parent	Structural pseudo-classes	3
E:nth-last-child(n)	an E element, the n-th child of its parent, counting from the last one	Structural pseudo-classes	3
E:nth-of-type(n)	an E element, the n-th sibling of its type	Structural pseudo-classes	3
E:nth-last-of-type(n)	an E element, the n-th sibling of its type, counting from the last one	Structural pseudo-classes	3
E:first-child	an E element, first child of its parent	Structural pseudo-classes	2
E:last-child	an E element, last child of its parent	Structural pseudo-classes	3
E:first-of-type	an E element, first sibling of its type	Structural pseudo-classes	3
E:last-of-type	an E element, last sibling of its type	Structural pseudo-classes	3
E:only-child	an E element, only child of its parent	Structural pseudo-classes	3
E:only-of-type	an E element, only sibling of its type	Structural pseudo-classes	3
E:empty	an E element that has no children (including text nodes)	Structural pseudo-classes	3
E:link E:visited	an E element being the source anchor of a hyperlink of which the target is not yet visited (:link) or already visited (:visited)	The link pseudo-classes	1
E:active E:hover E:focus	an E element during certain user actions	The user action pseudo-classes	1,2
E:target	an E element being the target of the referring URI	The target pseudo-class	3
E:lang(fr)	an element of type E in language "fr" (the document language specifies how language is determined)	The :lang() pseudo-class	2
E:enabled E:disabled	a user interface element E which is enabled or disabled	The UI element states pseudo-classes	3
E:checked	a user interface element E which is checked (for instance a radio-button or checkbox)	The UI element states pseudo-classes	3
E::first-line	the first formatted line of an E element	The ::first-line pseudo-element	1
E::first-letter	the first formatted letter of an E element	The ::first-letter pseudo-element	1
E::before	generated content before an E element	The ::before pseudo-element	2
E::after	generated content after an E element	The ::after pseudo-element	2
E.warning	an E element whose class is "warning" (the document language specifies how class is determined).	Class selectors	1
E#myid	an E element with ID equal to "myid".	ID selectors	1
E:not(s)	an E element that does not match simple selector s	Negation pseudo-class	3
E F	an F element descendant of an E element	Descendant combinator	1
E > F	an F element child of an E element	Child combinator	2
E + F	an F element immediately preceded by an E element	Adjacent sibling combinator	2
E ~ F	an F element preceded by an E element	General sibling combinator	3

source - http://www.w3.org/TR/css3-selectors/#selectors