So sadness is a normal reaction to many things such as loss, disappointment and even some problems. Feeling sad usually goes away quickly and it's easier to bounce back from. Depression is a mental illness and can effect the way you see and or understand yourself, it affects your mood. Depression can come for no reason at all and stay around a lot longer than the feeling of sadness, its more than just feeling down in the dumps. There are many factors that might show you may possibly be depressed, such as isolating yourself, loss of interest in things you normally enjoy, you can experience problems with your appetite and sleep and lastly thoughts about death.
