If I release some code and binaries, but I don't include any license at all with it, what are the legal terms that apply by default (in the US, where I am). I know that I automatically have copyright without doing anything, but what restrictions are there on it? If I upload my code to github and announce it as a free download / contribute at will, then are people allowed to modify and close source my work? I haven't said that they cannot, as a GPL would, but I don't feel that it would by default be acceptable to steal my work either.

So what can and cannot people do with code that is freely available, but has absolutely no licensing terms attached?

By the way, I know that it would be a good idea for me to pick a license and apply it to my code soon, but I'm still curious about this.

Edit

Thanks! So it looks like the consensus is that it starts out very restricted, and then my actions imply any further rights. If I just put software on my website with no security, it would be an infringement to download it. If I post a link to that download on a forum, then that would implicitly give permission to use it for free, but not distribute it or its derivatives (but you can modify it for your own use). If I put it on GitHub, then it is conveyed as FOSS. Again, this is probably not codified exactly in law but may be enough to be defensible in court. It's still a good idea to post a complete license to be safe.