Depression is common. More than 350 million people across the world – of all ages and from all communities – suffer from depression. In collaboration with WHO, writer and illustrator Matthew Johnstone tells the story of overcoming the "black dog of depression". The video resonates with millions of people and has recorded more than 5.5 million hits till the end of April 2015. Depression was described as a “black dog” like phenomenon constantly weighing down on the mind by former British Prime Minister Sir Winston Churchill.