Who should be the owner of wordpress’s file and directories?

I am using wordpress for developing a site. Many of the files and directories in /var/www/wordpress directory are having nobody:nogroup as owner including wordpress directory itself. My question is whether it is safe to have this ownership or should i change it to www-data:www-data. I am having only two users one is admin and one who will work on the site(for uploading some documents through a interface developed by admin using php on wordpress pages). Rest use it for viewing purpose and downloading those documents. It is more of a permission question than wordpress question. Thats why i asked it here. So that it will also help others who will use CMS like wordpress for website development.

Thanks