EPP stands for Extensible Provisioning Protocol: An application layer client-server protocol for the provisioning and management of objects stored in a shared central repository. Specified in XML, the protocol defines generic object management operations and an extensible framework that maps protocol operations to objects.

This method is used to verify .org, .info, .biz, .us, .cn, .com.cn, .net.cn, .org.cn, .cn, .tw, .jp and .in domains only.  This may change at any time depending upon registry requirements. 

When an EPP transfer order is created, an "authorization key" or "EPP key" is required for each domain name to be transferred. Per ICANN regulations, a verification email or fax transfer authorization is also required.

Authorization (or EPP) keys/codes are generated by the current registrar and verified through the global registries for validity.