The EPP key (Authorization code) is one of the safeguards against unauthorized transfers of domain name registrations and it protects your rights as a domain owner. The EPP key is required when transferring .com, .net, .org, .biz, .info and .us domain names. It is not possible to initiate a domain name transfer for these domains without an EPP code.
If your domain is registered by HostMDS you can find the EPP key in your Client area under the domain name section.
If your domain is NOT registered by HostMDS you will need to contact your current registrar to obtain the EPP key code before being able to initiate a domain transfer.