1st screen: a television, Blu-ray player, set-top-box, or similar device.
2nd screen: a smartphone, tablet, or similar device.
DIAL Server: a device implementing the server side of the DIAL protocol, usually a 1st screen device.
DIAL Client: a device that can discover and launch applications on a DIAL server – usually a 2nd screen device.
The DIAL protocol has two components, DIAL Service Discovery and the DIAL REST Service.[4] The DIAL Service Discovery enables a DIAL client device to discover DIAL servers on its local network segment and obtain access to the DIAL REST Service on those devices. The DIAL REST Service enables a DIAL client to query, launch and optionally stop applications on a DIAL Server device.