The Extensible Provisioning Protocol (EPP) is a flexible protocol designed for allocating objects within registries over the Internet. The motivation for the creation of EPP was to create a robust and flexible protocol that could provide communication between domain name registries and domain name registrars.

These transactions are required whenever a domain name is registered or renewed, thereby also preventing domain hijacking. Prior to its introduction, registries had no uniform approach, and many different proprietary interfaces existed. While its use for domain names was the initial driver, the protocol is designed to be usable for any kind of ordering and fulfilment system.

EPP is based on XML – a structured, text-based format. The underlying network transport is not fixed, although the only currently specified method is over TCP. The protocol has been designed with the flexibility to allow it to use other transports such as BEEP, SMTP, or SOAP.
Source: Extensible Provisioning Protocol(EPP)