Depression is a type of mood disorder in which a person is unable to carry out his/her day-to-day activities properly and may also go through suicidal feelings and begin to think that it isn't worth to live life. It is also known as Major Depressive Disorder or Clinical Depression, which greatly affects a person's way of thinking, feeling and behavior that can lead to a variety of emotional and physical problems. It causes a person to have constant feelings of sadness and loss of interest.

All classes of people be it adults or children, suffer through the problem of depressive disorder. The people with depressive disorder exhibit problems in carrying out normal day-to-day activities such as school, work, social activities, relationships with others, etc.

Depression is caused due to different reasons and on the basis of the cause of depression, it has been categorized into various types. Often people feeling low resort themselves to the use of drugs and alcohol in an attempt to make their pain go away. The extended use of these substances might cause one to become addicted to its use which results in lowering the self-esteem of the person and his/her mood may become even lower than usual over the duration of the use of these substances. All of this causes depression. Depression can also be caused due to general medical conditions if a person is suffering from a mental illness or a physical illness for a long period of time.

The depressive disorder highly interferes with the psychology of the brain to a great extent. Therefore, many different types of psychological theories have been formulated which provide evidence-based explanations as to why the people behave, think and feel in a particular manner.

It is crucial that proper diagnosis of the illness is made before moving forward with the treatment of depression. Different types of depression treatment methods have been formulated for treating different types of depression. Proper diagnosis of depression is carried out through the means of face-to-face interviews, physical exams, medical history, and several lab tests.