Why do Writers Write

When there is something to talk about, you talk about it for others to know what you are feeling, what life has brought upon you. The same happens to writers, if you have something to say and you want everybody to know it, you write. Or, perhaps, when you are so isolated from the outside world that you only want a sheet of paper to know what you are thinking. 

In conclusion, writing is a way of expressing feelings or thoughts in paper. If you want to get rid of some experiences but want them to "stay there" forever until a lonely voyager, who maybe is feeling in a similar way, finds them, reads them and ends up remembering you, then what you have to do is simply to use a pen and start writing.