Courage, as defined in Wikipedia, the free encyclopedia, is known as bravery and fortitude, is the ability to confront fear, pain, danger, uncertainty or intimidation. It can be divided into "physical courage" — in face of physical pain, hardship, and threat of death — and "moral courage" — in the face of shame, scandal, and discouragement. (http://en.wikipedia.org/wiki/Courage)

“Courage is a special kind of knowledge: the knowledge of how to fear what ought to be feared and how not to fear what ought not to be feared.” David Ben-Gurion (1886-1973), Prime Minister of Israel

There are more quotes on what is courage at http://www.wisdomquotes.com/cat_courage.html. Some of the quotes I find it more applicable in today's life are :-

To Bernadette Devlin, courage is "Yesterday I dared to struggle. Today I dare to win."

To Buckminster Fuller, courage is "Dare to be naive."

To Dorothy Thompson, courage is the power to overcome the obstacles in life while affirming that life with its sorrows is good.

To Winston Churchill, "Courage is going from failure to failure without losing enthusiasm."

All this itself, may not clearly illustrate what is courage. Perhaps this little joke helps :)

A graduating student was attempting a paper on courage. After writing about half a page on it, he found that the more he wrote, he more confused he got over the topic. He decided to take a drastic action and show what it means by courage. He tore away the page and wrote three big words across the page "This is Courage!".