moderating article posting

I’m new to WordPress, but currently blown away by it’s wonderfulness. There’s something I can’t quite work out though so hopefully somewhere here can help.

I’ve set up a blog style site, but I would like anyone to be able to enter an article. But equally I don’t just want to allow anyone to post anything at any time! I see you can allow anyone to register, but is there a way to not allow their articles to show unless I (as admin) have approved them?
The other option I can think of is some kind of submission form, where they can type in an article, I view it and click to approve for publication.

I suspect there must be a widget out there which can do that, but I’m not sure how to find it? Thanks!