Showing VS Telling

From The Writerium - the wiki for writers

Something that is told requires the reader to read actively, think about the passage, and recreate a fictional reality; whereas anything shown contains explicit instructions so the reader can read passively and lose himself in the precise reality that the author specifies, although he or she cannot specify everything, and there is always some level of imagination involved.

Passages that are told often rely on explicit verbs and adjectives to paint the scene, whereas parts that are shown tend to rely more on presenting a visual that allows the reader to draw his or her own conclusions about what is happening.

Popular myth has it that showing is always the better method to use - something debunked by Orson Scott Card:

"'Showing' is so terribly time consuming that it is to be used only for dramatic scenes. The objective is to get the right balance of telling versus showing, action versus summarization."

The consensus among writers seems to be that neutral qualities - ie. what something looks like, smells like, sounds like, etc., should be told, whereas emotional and moral qualities must be shown. Put another way, there is nothing wrong with telling a reader that Mal has brown hair, but if he is angry it is better to describe how is expression, voice and behavior are angry, rather than simply stating that he was angry.

Examples

Telling: He was happy.

Showing: He had a broad grin on his face and his eyes twinkled.

Telling: The angry-looking woman walked up and slapped him smartly.

Showing: The woman strode toward him, eyes narrowed and teeth clenched. She pulled back her arm and let fly a stinging blow to his face.