What is depression?
Everyone has ups and downs. Sometimes you might feel a bit low, for lots of different reasons. People may say that they are feeling depressed when they are feeling down, but this does not always mean that they have depression.
Depression is a long lasting low mood disorder. It affects your ability to do everyday things, feel pleasure or take interest in activities.
Depression is: 

• a mental illness that is recognised around the world,

• common - it affects about one in ten of us,

• something that anyone can get, and

• treatable.

Depression is not:

• something you can 'snap out of’,

• a sign of weakness,

• something that everyone experiences, or

• something that lasts forever as one episode.

Doctors might describe depression as 'mild', 'moderate' or 'severe'. Your doctor may offer you different treatments depending on how they describe it.
How common is depression?
Depression can affect people of any age, including children. It is one of the most common mental illnesses. The number of people who have depression may be higher than this because not everyone with depression goes to their GP. 
What are the different types of depression?
You might have heard a number of terms used to describe depression. In this section, we explain what some of these terms mean.
Clinical depression
Clinical depression is a common term, but it is not a formal diagnosis. People sometimes say ‘clinical diagnosis’ to just mean they have been diagnosed by a doctor.
Depressive episode
Your doctor might say that you are going through a 'depressive episode'. This is the formal name that doctors give depression when they make a diagnosis. They may say that you are going through a 'mild', 'moderate' or 'severe' episode.
Recurrent depressive disorder
If you have had repeated episodes of depression, your doctor might say that you have recurrent depressive disorder. They may say that your current episode is 'mild', 'moderate' or 'severe'.
Reactive depression
If your doctor thinks that your episode of depression was caused by particular stressful events in your life, they may say that it is reactive. For example, divorce, job or money worries. This is sometimes separated from an adjustment disorder, where you may struggle with some symptoms of depression because of adapting to a major change in your life. Such as separation from people, retirement or migrating to a new area.
Severe depressive episode with psychotic symptoms
If you are going through a severe episode of depression, you may get hallucinations or delusions. A hallucination means you might hear, see, smell, taste or feel things that aren’t real. A delusion means that you might believe things that don’t match reality. These symptoms are called psychosis.
Dysthymia
Your doctor might diagnose you with dysthymia if you have felt low for several years, but the symptoms are not severe enough, or the episodes are not long enough for a doctor to diagnose recurrent depressive disorder. 
Cyclothymia
Your doctor might diagnose cyclothymia if you struggle with persistently unstable moods. You might have several periods of depression and periods of mild elation. These periods of depression or elation are not severe enough or long enough to diagnose recurrent depression or bipolar disorder. It is a common illness which affects more than 1 in 10 women within 1 year of having a baby. You may get symptoms that are similar to those in other types of depression.
Seasonal affective disorder (SAD)
This type of depression affects you at the same time of year, usually in the winter. The symptoms are similar to depression, but some people find they sleep more rather than less, and crave carbohydrates like chocolate, cakes and bread.
Manic depression
Manic depression is the old name for bipolar disorder. It is a different illness to depression. People with this illness have highs (mania) and lows (depression).