Depression can manifest as a large variety of symptoms, most often feelings of sadness or despair that do not go away. Depression can negatively affect a person's ability to function effectively in the activities of daily living, such as going to work and school, caring for family, and taking care of basic needs. More than 20 million people in the United States have depression, according to the National Institutes of Health.Depression is often thought of as experiencing feelings of sadness, "having the blues", or being disheartened. However, there is a major difference between having normal feelings of sadness in reaction to a situation, such as a death in the family, and having depression. Normal feelings of sadness, although painful, generally resolve after a short time. For people with depression, feelings of sadness linger beyond a short time and intensify to the point that they interfere with the