According to the NHS, around one in 10 people will suffer from depression during their lifetime. Considering this relatively high statistic, it's perhaps surprising that many of us know so little about the illness.
The above video from ASAP Science helps to explain the science behind the depression.
In the past, depression has often been described as "a chemical balance in the brain", but in reality, it is far more complex.
According to the video, when we look at the brain of a depressed person, an area of the brain called the hippocampus appears to be much smaller than a person who is not depressed.
The hippocampus controls memory and emotion, explaining why the most regular symptom of depression is having a low mood. It continues to shrink the longer the person is depressed, but certain medication can help promote brain cell growth and reverse the effect.
The video also explains more about how anti-depressants work and reveals the type of people who are genetically more likely to suffer from the illness.
Most importantly, it also highlights that depression is not something that people can simply "snap out" of. Depression is a disease with a biological basis along with psychological and social implications.