Each site has unique identifier, also called a <em>UUID</em>, which identifies the site to the system in any instance of the site, as long as the site instances have been reproduced as clones (cloning is when the codebase and database are copied to create a new site instance). When site instances are cloned, a "dev" instance of the site has the same UUID as the "live" instance. When site instances share the same UUID, configuration can be exported from one instance to another.