Possible Values content can comprise a list of strings, URLs that resolve to images or other resources, counters or keyword defined elements. These are added as inline, block or marker elements before or after selected elements depending on the pseudo element selector used. However the statement that creates the content can set the display of the content to be a block, or other kind of element, rather than an inline element. For more on quotes, see the quotes property below. Think of them as super-charged versions of numbered lists.
Counters have a name, and a style.
You create a counter using the counter function, then use them in conjunction with the content property to insert markers into a document. There are two forms of the counter function, the counter form and the counters form. These styles are the same as those for elements of type list-style. When the browser encounters a counter function, it determines the value of that counter at this point of the document, then inserts it into the document in the nominated style. See the section on counters below for more detail.