How is an Organizational Culture Created?

I have been wondering where I can find out more information on a topic that has come to my attention lately. I was reading and I came across mention of an Organizational Culture, and I am wondering how exactly these are created. Is this just something that happens due to the people who are working there when the company first gets started and how they deal with different issues that come up? I am also wondering whether this is something that is set in stone or something that evolves as time goes on. Where can I go to find out more about this idea?