Fundamental to Meteor is the concept of real-time applications, with the client and server interacting with each other using the principle of data on the wire. The folks at Meteor have developed a protocol for this real-time client-server communication, called the Distributed Data Protocol (DDP). As with everything else in Meteor, DDP is a discreet (albeit core) library, which you can use separately. The recipes in this chapter will show you how DDP works and give you some ideas about what you can do with it outside of its default use in Meteor.