I remember always being told this all the way through school. Stories have three parts, a Start, Middle and an Ending. All my teachers told me this and at the time I agreed.
This fact is true when you consider that stories are all fundamentally just journeys, but when you consider that the best endings are always new beginnings, it is false.
For example the end of the first Matrix film is a phone conversation from Neo (with his new awakened abilities) telling the Machines that there is going to be some changes. Then he steps out of the phone-box and does his Superman thing. This allows the audience to imagine how things might change as the credits roll and it is a great way to make the audience keep thinking about a film (or whatever) long after they have seen, read or experienced (whatever form of medium it is).
This post for example is finite and has a distinct ending because it only has one running thread, that is me having a conversation with you. If however I was to have multiple interacting threads like for example characters, then I could construct personalities or traits for those threads and that would allow you to become connected with them and then I could construct a continuing future for those threads beyond the ending of the text, kind of like I did with my Coding A Feature A Day post.
This text however has an even more basic link to you, me talking through your internal reading monologue (yes the voice inside your head) and that can be used for you to question ideas or fill in missing ____ of txt. I can't see a way of doing the multiple thread thing in this post, but if I was to talk about a night-out and introduce friends and then talk about what happened to those friends, then the multiple thread thing would happen and I could leave it open for you to dwell on the outcome or continuation. So the end of a stories text doesn't have to be the end of the story at all.
Rant over, you can go and look at some porn now, OW! Puppies!