Sorrow, grief, temptation. Just one of the few things we associate with depression. Depression for me, more than just a 10 lettered word and why not, having an on and off for 5 years relationship with such state of mind. Losing hair, being sick, mood swings, planning to leave the house or even put an end to the misery by any necessary force are just a mere symptoms of what depression is.
It's like this never-ending labyrinth to which the destination leads to another. It's when all the hope is lost, having no one to look up to. Faith and belief lose their existence. Fear itself now has no meaning. One becomes immune to pain and grief. Fantasies and past becomes the savior but slow poison of present reality still making it worse. For me a person with real depression is the person who would expect it to be the last. It may be your best friend, may be a single father of 3 working selling fruits, or just a guy living a perfect life in your opinion. It has no barriers to how it occurs, but more commonly on rejections. Example son getting kicked out of private school, rejection on a job, parents not allowing you to by a brand new cell phone, friends giving attention to someone/something else, and rejections fame or even love. Basically, it can be precisely described definitions by the economists on wants and needs. Depression can also be lead by losing something, either of materialistic or intrinsic value, let's say, soccer coach seeing his team on a 10 game losing streak and on the brink of relegation, Best friend dying in a car accident, branded wrist watch getting stolen.
Person who's depressed can be labeled as selfish, since he gets so involved within the issues causing the depression, like a black hole, it has an effect on others around him and also drag others into it. He starts to take pity on himself rather than finding the solution or the cause or to ease the pain. Other issues don't matter anymore so getting into arguments every now and then and various other reasons. But again, you can never judge the depth and intensity of the emotion and desire which triggers depression in a person.
Physical depression for me is fake. Wearing mascara, getting tattoos and piercings, wearing makeup and listening to death metal. Person with "real" depression doesn't need it, in his mind he gets scarred over and over and over.
Pity, I won't type down the solutions to pacify depression. Basically because I don't want to lie. And what I would say, I'm pretty sure won't be something I would be implementing on myself anytime soon. So if you have a solution for someone, put them in your own shoes before making a judgment. At least this is what I would do.