In this chapter, we discussed how ZeroMQ sockets differ from traditional TCP sockets. Later on, we discussed limiting the number of sockets and setting I/O threads. We also discussed how to work with multiple sockets and how we could send multi-part messages. In the last section of this chapter, we learned about CZMQ, a high-level C binding library for ZeroMQ, which would minimize the difference between ZeroMQ v2.x and ZeroMQ v3.x.