It's a biological illness which affects one's thoughts and feelings. Depression affects about 340 million people in the world today.
Depression can occur at any age.
It's very common in adolescents and elderly individuals. Often it is difficult for someone with severe depression to participate in daily activities. They often withdraw from family members and friends. About half of all cases of depression go unrecognized and untreated. Many people are view depression as a sign of personal weakness or failure, and are afraid to seek treatment for fear of being stigmatized.