Depression

*Depression can be both acquired and genetical
Acquired: 1) death of close friends/relatives/family members 
2) breakups 
3)professional failure 
4) financial loss
5)accidents etc
*Depression is to be diagnosed by a psychiatrist or a psychologist
psychiatrist studies to get a medical degree in the field of mental health either to attain an MD (doctor of medicine) or DO (doctor of osteopathic medicine). After they graduate with either of the degrees, they write an exam to gain a license to practice their field in a chosen state.

A psychologist studies a graduate program in medicine for a period of four or six years to attain a PhD (doctor of philosophy) or PsyD (doctor of psychology) degree. They will also be required to complete an exam to gain license in a chosen state to practice professionally.  

Smiling Depression 
It is like high functioning form of this mood disorder known as Depression.
Its a condition where persons maybe smiling from outside but inside he may be dying.
Person suffering from this are at higher risk because they don't share and suffer alone.
Suicide is a big risk.
the main and the biggest problem of depression is hidding it and not seeking help.
This hidden feelings keeps on growing and the end results can be very dangerous.

People do not discuss how are they feeling and thus suffer alone. They wear a mask of smile and try hiding what they are going through.

Depression is not a disease its just a disorder which is treatable. In other and more simpler words its a 'phase' which will paas.
One must ask for right help at right time.