Depression is also called as Clinical depression, Dysthymic disorder, Major depressive disorder, and Unipolar depression

Depression is a serious medical illness that involves the brain. It's more than just a feeling of being "down in the dumps" or "blue" for a few days. If you are one of the more than 20 million people in the United States who have depression, the feelings do not go away. They persist and interfere with your everyday life. Depression can run in families, and usually starts between the ages of 15 and 30. It is much more common in women. Women can also get postpartum depression after the birth of a baby. Some people get seasonal affective disorder in the winter. Depression is one part of bipolar disorder. There are effective treatments for depression, including antidepressants and talk therapy. Most people do best by using both.

Everyone experiences times when they are unhappy. Sometimes this is because of a loss, or a change. The feeling of sadness, though, is appropriate and transitory. When such feelings persist and impair daily life, they may signal an underlying depressive illness. So it is the severity and duration of symptoms, plus the presence of other features, that help distinguish this normal sadness from a depressive disorder.

Depression is more than just a mood disorder, it is a real illness that not only affects one's mood and thoughts but also appetite, sleep patterns and one's self esteem.

It may also involve physical symptoms, such as stomach pains, headaches and rapid heartbeat. There are several different types of depression, so you will hear terms like major depression, endogenous depression, chronic depression, and so on. These terms tend to describe the predominant symptoms, their severity or their duration.

A depressive disorder is an illness that involves the body, mood, and thoughts. It affects the way a person eats and sleeps, the way one feels about oneself, and the way one thinks about things. A depressive disorder is not the same as a passing blue mood. It is not a sign of personal weakness or a condition that can be willed or wished away. People with a depressive illness cannot merely "pull themselves together" and get better. Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people who suffer from depression.

How do you get Depression?

• The causes are complex. It may be a combination of changes in circumstance, changes in the chemical balance of the brain cells, and genetic factors may also be involved.
• Some types of depression run in families.
• However, there are many other factors that can be involved, such as a stressful environment, low self-esteem, stress, bereavement, chronic illness, difficult relationships, financial problems or any unwelcome change in your life pattern.

Conditions when you feel that you are depressed:

• It's hard to make up your mind. You forget lots of things, and it's hard to concentrate.
• Life seems meaningless or like nothing good is ever going to happen again. 
• You don't feel like doing a lot of the things you used to like-- like music, sports, being with friends, going out-- and you want to be left alone most of the time.  
• You feel guilty for no real reason; you feel like you're no good; you've lost your confidence.  
• You feel restless and tired most of the time.  
• You feel sad or cry a lot and it doesn't go away.  
• You get irritated often. Little things make you lose your temper; you overreact. 
• You have a negative attitude a lot of the time, or it seems like you have no feelings. 
• You think about death, or feel like you're dying, or have thoughts about committing suicide
• Your eating habits change; you've lost your appetite or you eat a lot more. 
• Your sleep pattern changes; you start sleeping a lot more or you have trouble falling asleep at night. Or you wake up really early most mornings and can't get back to sleep.

Key points about depression in adolescence 

• Both biological and developmental factors contribute to depression in adolescence. If Bipolar Disorder or psychosis is suspected biological causes would need to be examined. 
• Depression in this age group should be taken seriously. Youth suicide is the third most common cause of death in this age group.
• In tracking down difficulties it can help to consider some of the areas that the adolescent is dealing with: school, family, peer group and intimate and/or sexual relationships.
• It can be hard to distinguish adolescent turmoil from depressive illness, especially as the young person is also forging new roles within the family and struggling with independence, and academic and career decisions.