Clinical depression goes by many names -- depression, "the blues," biological depression, major depression. But it all refers to the same thing: feeling sad and depressed for weeks or months on end (not just a passing blue mood). This feeling is most often accompanied by feelings of hopelessness, a lack of energy (or feeling "weighed down"), and taking little or no pleasure in things that gave you joy in the past. A person who's depressed just "can't get moving" and feels completely unmotivated to do just about anything. Even simple things -- like getting dressed in the morning or eating -- become large obstacles in daily life.