Twitter tutorial for complete newbies

Over a year ago, I've put together a very basic introduction to Twitter for my colleagues. At the time, Facebook seemed to be a more familiar tool for advocacy in our group, whereas Twitter's potential remained somehow unexplored.

"What can you possibly say in 140 characters"? "What on Earth is a hashtag"? "How do you include multimedia links on Twitter"? "Can you really hook a politician on Twitter?"

I will write more extensively about it in my next posts. In the meantime, enjoy this introduction.