This sections documents various protocols and transports that are
available in the distribution.

(((protocol)))
Protocols represent "`patterns`" of communication, such as
request/reply, publish/subscribe, and so forth.
A given <<nng_socket.5#,socket>> is created with exactly one protocol, and that
protocol defines the key behavior of the socket.

(((transport)))
Conversely, transports are the underlying mechansims by which messages
are moved between participants, such as TCP/IP or UNIX domain IPC.
A given <<nng_socket.5#,socket>> may be using several transports at the same
time.