The truth is that depression affects people in different ways and the way people view it and experience it varies a lot. Some people experience depression from early age, in teens or as a young adult or have their first experience of it later on in their lifetime. There are also different reasons why people get it there isn't just one correct standard way. It can be for just short duration of time following a stressful event or difficult change etc or happen now and again, it can come and go, reappear. Others have it more severely, for much longer ongoing period of time and affecting their everyday life.