In Drupal, content is categorized via taxonomy. Most widgets on a site will pull content that has been tagged with a specific term.
There are two ways that you can use taxonomy terms to present content. The first is the nodequeue, which adds content tagged with a specific term to a queue, which can then be ordered by a content creator. A good example of this is the Slideshow, whereby Contributors can sort individual slides in order to promote the most important content.
The second way is the direct use of the taxonomy term. This is used when a specific sort order has been chosen for a widget. Taxonomy terms are used in the university’s online calendar widget, uoCal, which displays events in chronological order.