"Depression is a mood disorder", so start many descriptions of the illness. That is a gross understatement. Depression does indeed seriously affect your mood, but that is just the tip of the iceberg. A clinical depression can be an incapacitating illness, affecting your ability to perform tasks that require concentration and rendering you unable to work.
By writing this document we hope to provide you with the knowledge everyone should have about their mental well-being. Depression is not an unavoidable fate. It is physical.
The good news is that you can recover and yes, even learn to be happier than you have ever been before.
A wiki about depression also downloadable as pdf.
Thanks David Rothman: List of Medical Wikis