Can I copy/paste my layout to a different domain/host?

I’m a new user and I’m really enjoying my experience so far. My question for now is, is it possible to transfer a completed layout/site to a different domain on the same host and/or a different host? I use one domain to do my testing with so that I don’t mess up my live site, then when I’m satisfied I want to copy the changes to the main domain. I’ve never purchased a WordPress theme before so I didn’t know if it was possible to backup/restore the entire thing to a different domain even on a different host?

Thanks in advance