Right now I am actually struggling through it. I think I am doing relatively better but at the same time I know it isn't over.

There are many ways people can describe depression, but at the same time it can be hard to comprehend. Someone once said that it can be summarized as the loss of hope. This is pretty accurate, I remember feeling like the depression would never end and that I should just give up at trying. I remember that hopeless feeling and even hating the idea of hope.

Also, I think of depression acting in spirals. When you go through day-to-day life with depression, you are on the brink of messing up. If something goes wrong like missing school work or whatever, you feel guilty and hopeless and like a failure and you want to lay down in bed. This leads to you being less productive and accomplishing less and therefore you feel worse. It becomes this loop that gets worse, while the whole time you are miserable. Once you somehow manage to get your bearing again, you go back to that barely surviving state where a bad event could tip you over the edge again. (I remember a post on /r/depression describing this like walking though a river against the current, and every time you spiral is like drowning in the current, where you lose your orientation more and more until you somehow gain balance again.)

Now for me, depression isn't as severe. Now it is like apathy. I care less about good or bad things that come my way. When someone does something nice for me, I literally can't feel gratefulness, but act that way because I know it is the right thing to do. I can't see a future for me yet and I still am reluctant to be hopeful on things.

There is a bit more to depression and my own than that, but I think it's a good enough answer.

As for overcoming, I don't think you 100% can. There is no "cure" for depression. You can take pills to subdue its effects and work very hard to live with it. This is why depression is hard to overcome. How can you fight a battle against your mind when you are hopeless and would want nothing more than to lay down and do nothing to stop it.