EPP Code Stands for Extensible Provisioning Protocol which is alpha-numeric code required to transfer domain from one registrar to another registrar. EPP Code is also known as Authorisation Key Or Transfer Secret Key.
Authorization (or EPP) keys/codes are generated by the current registrar and verified through the global registries for validity. Authorization (EPP) keys are a security code required by the registry for domain transfer, thus are unique to every domain name. No two EPP/authorization keys are the same, thus if you are transferring more than one EPP domain, you will need to obtain each domain's specific code separately for the security reasons.
EPP key is one of the security precautions to protect your domain being transferred illegally. If anyone other than your registrar requests your EPP Key, you should ensure that you validate the request.
EPP domains: (.com, .net, .org, .info, .biz, .us, .cn, .com.cn, .net.cn, .org.cn, .cn, .tw, and .in)
1) Above mentioned domain TLDs require an EPP/authorization key for transfer.
2) Only Current registrar can generate EPP Code which is automatically sent to Registrant email address of a domain.
3) Gaining Registrar initiates transfer request for the domain with the EPP/authorization key provided by the customer. This request automatically goes to Registrant and Administrative contact email address. Once domain transfer request is accepted, domain is transferred successfully within 5-7 days under new registrar account.
If you are having difficulties gaining the EPP Code/ Authorization Key for your domain from your current registrar in regards to transferring the domain, you can contact ICANN to help you transfer the domain name.