What does "hanging chad" mean?

The election for president, Congress and a host of state and local offices and issues appears as close as the 2000 overtime contest that wrote the term "hanging chad" into the nation's lexicon. And if anything, passions about this contest are even more intense. (Related link: When polls open, close)
A chad is the tiny piece of paper which is pushed out of a punch-card style voting card by the voter to indicate his choice. It must be pushed completely out to be valid; if the voter changes his mind in mid-push, then the chad may be incompletely separated from the paper card, and be left 'hanging'. There was much argument over these during the 2000 Florida count.