Github License and Code Protection
Assume I want to post a project of mine to github. I want people to be able to see it, clone it, and maybe even contribute and make changes that I'll check and apply if they are good. BUT, I obviously don't want people to copy my code and post it as it's theirs... or even just copy certain parts of it. What license should I pick? And how can I make sure that people don't copy my code? Are the licenses free?