Characters do more than just talk at each other. They move – with grace, in anger, to disguise emotion – and movement tells even more about them than their words.
Understanding and using action to tell a story is both powerful and organic – a naturally evolving way to strong characterization.
What is body language? Google it on the web – you’ll find dozens of books by experts from all sides: psychology, business, spiritual growth, forensic investigations and many, many more, all useful in their own way. I even watched a fascinating TV program the other night on spotting lies and bought the book because of it.