Extensible Provisioning Protocol or an EPP code is an authorization code assigned to a domain name. This code is unique and it is used for authentication during a domain name transfer, renewal, and registration. Its purpose is to provide a directive between the registry and the registrar.
This code provides security against unauthorized domain name transfers and it's obtained either directly from the registrar or through the domain name control panel.
All EPP codes are case sensitive, which means that the text is sensitive to the capitalization of the letters.
Some TLDs require an EPP code for a domain transfer. Those TLDs are .com, .org, .net, .biz, .info, .mobi, .eu, .us, .me and many more.