If you're still checking your answers here and it's not too late...I will try and briefly describe it for you basing part of what I know on my own experience.

Depression is a debilitating disease that inhibits one's desire to accomplish even the simplest of daily tasks.  Depression doesn't have the energy to even think up a statement like that let alone care or even get up in the morning.  It would rather sleep!  That's why you're not getting a lot of response here I think.  Curious though, did you pick this subject yourself?

Anyway, depression is, technically speaking, something to do with a lack of seratonin in the brain and the neurotransmitters not firing properly.  I don't want to say more than that for fear of explaining it improperly (so don't quote me ), and giving you an "F" on your next report.  Idea:  look up Depression and look up Seratonin in "Wikipedia" on-line. It's a valuable source for information.

Depression carries itself out in different ways and at different levels of pain and discomfort from crying to anger.  I have had different bouts with depression.  I actually thought I came out of it once after twenty years, but apparently as I have learned it has a remission cycle (in Major Depression).  I think it's always been in my genetic make-up. 

However, anybody can go into a depression after a traumatic event or situation in their life, because we all have levels of dopamine (a chemical that affects our moods) and the chemicals in our brain literally change when we get hurt.  It's just that some people bounce back a little more readily if they are not already lacking seratonin.  It still takes positive strategies to overcome hardship though.  That's why it is highly recommended that individuals seek therapy along with any drug TX.  Like with anything, you have to understand the problem before you can find a solution, right?  It's rocket science.

The controversy is whether depression is a disease or a symptom.  The question I use to desparately need to know the answer to was, "Was I born with this?  I'm doing everything to make it go away and it won't."  I think I was born with low seratonin levels from the beginning and the situations in my life took a tremendous amount of energy to overcome.  I don't think I could've done it without the help of medications, doctors and people.  I could blame my impulsiveness on my disease of depression, or I could blame my depression on my impulsiveness.  See what I mean?  It goes hand in hand and it's a vicious cycle.  Sometimes a very deadly one.

 You have to learn how to be positive when you're living with depression because it sucks you in and the more it sucks you in, the more negative you think.  Ask yourself, how it would feel to be told you're stupid and ugly throughout the course of your childhood.  Forest Gump once said, "Stupid is as stupid does" and telling me I was stupid was the stupidist thing anyone ever told me.  Consequently I grew up thinking I was stupid and I don't think I'm ugly but sometimes a little voice comes in my head and tells me so. 

Depression can be embarrassing, painful and lead to addiction or death if left untreated.  Therefore, on a last note, the worst thing a depressed person can do is not ask for help  and unfortunately that is the paradox of depression.

Hope this helped.  If you have anymore questions I'll try to help answer them.  Depression has sort of been my life.

Short answer: It's a living hell.

Longer answer: Imagine feeling, every day, most days of the week, for years on end, waking up and feeling that life is a cosmic joke; that there is no purpose to life; that you can find little joy in anything; that doing everyday activities is tiring to impossible; that you wish you had never been born; that death seems preferable to the ongoing struggle of living. That's depression. I've had it probably since I was 13, long before there were any pharmaceutical interventions that were any good. It's much better now (my depression) but there are still times when hormonal fluctuations mess with my brain and it comes back briefly. I fear and dislike those times.

 Sleep is difficult with depression. Sometimes, you sleep too much. Sometimes, you hardly sleep at all. Me? I went through insomnia, then started oversleeping, then I got tired of oversleeping, so I made myself stay up once, and got stuck in insomnia again. Now, I'm exhausted all the time, and have early morning wakefulness. I'm exhausted, and sleep when I can, but I never get more than three to four hours. Sometimes, it's nice to sleep a lot. It's an escape.

Eating is a little odd too. I went through a phase where I felt too sick to eat, so I didn't. Now, I'm going through a phase where it seems like all I do is eat. My stomach's been feeling the same, and I think I'm about to hit a no-eating phase again.

Going through the day is a joke. Everything you do is the epitome of futility.

Going to class? Ha! Learning and getting a degree is useless, you're too much of a colossal idiot to really learn, much less do anything productive with that knowledge. And what are you going to do with that degree anyway? No one would hire an incompetent fool like you. You have no talent in any field anyway, you're not cut out for anything. Essentially, you're a burden on society.

Work? Once again, if you were living on your own, you'd be out on the street, you're so incompetent with everything, especially the things that matter, like money.

Relationships? Basically, you're not going to find your one, and you're just a disappointmet and a downer to the one you're with. Forget your dreams of finding anyone, you're always going to be alone, just like you always have been. You don't even have any real friends. You're not worth sticking around for, never have been, never will be.

Leisure? It's an accomplishment to focus enough to read a book. And that same lack of focus affects you academically. You can't focus on homework, and it's wasted on you. Why do it?

You're guilty, about every little thing. You're not worthy of any sort of happiness. Nothing's going to change for you, and you can't do anything to change it.

You want to die. You don't even want to use the energy to kill yourself, you just want to lay down and dissolve. But, guilt kicks in, and you can't even kill yourself, because that would hurt your parents, or the few who do care about you. So you feel even more trapped.

You feel like you're weak. Knowing that your depression might have some physiological cause only makes you feel defunct physically and mentally. You feel weak and spineless. You do your best to hide it, because if anyone catches on, you're terrified of being put on meds, being carted off to Bedlam, or having to spill your guts to someone else. You feel too scummy to feel like you can really open up to anyone. So any time someone expresses affection for you, you feel like you've decieved them, and like if they knew how worthless you really were, they'd be disgusted, and never want to have anything to do with you.

I think I've covered all the bases. There's probably more that I left out, like the basic lack of interest, even in the things that you used to love, but I think I got you to a point that you can understand.