You're new here and you've asked what seems to you a reasonable question. You've been down-voted because you haven't done your homework. From http://ycombinat

You're new here and you've asked what seems to you a reasonable question. You've been down-voted because you haven't done your homework. From http://ycombinator.com/newsguidelines.html http://ycombinator.com/newsguidelines.html : On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity. I've re-up-voted you because I don't think your question deserves to be at -4, even though it doesn't really add value to the site.