Transferring a domain name from one company to another usually involves the use of a unique domain name authorization code, which different registrar companies call an EPP key, a domain password or an Auth code. This code can be used as a security mechanism against unapproved transfer attempts with all gTLD and with most ccTLD extensions. The code can be obtained only by the owner of the specific domain name and is issued by the present domain registrar company. It must be given to the new domain registrar company because the transfer cannot be started without it. The code is case-sensitive and usually comprises of digits and special characters, so as to prevent unauthenticated persons from cracking it. Some registrars even alter the codes of domain names registered through them periodically for even greater security.