What is a set of agreed-upon instructions designed to allow computers to communicate to each other across a network connection?

Answer 1

Computers use communication protocols to communicate with each other. Just as humans generally communicate with each other using a common language, computers must do the same. A protocol defines the language the computers will use and both computers must agree upon which protocol to use, via a standard "handshake" protocol -- a simple two-way communication that establishes a connection as well as the protocol that will be used for the actual communication. Only when both sides agree upon the actual protocol can communication begin.

As technology develops, protocols must evolve. Thus we have seen many ways for computers and devices to communicate and interconnect with each other over the years, each with their own set of protocols, each suited to a specific or general task. In the past we've seen COM, LPT, Ethernet, USB, FireWire and, more recently, wireless devices. Ethernet and wireless provide the basic transport system between any two computers today and often work together using intermediate devices, including wireless routers (which are themselves just simple computers). Without a common protocol, communication between all these devices would be impossible.

The most prevalent protocol in use today is TCP/IP, without which the internet would not work. TCP/IP is actually two separate protocols: Transmission Control Protocol and Internet Protocol, but they work together with a third protocol, UDP (user datagram protocol), to provide a multi-layered suite of protocols. The top layer, the application level, is further split into separate protocols including HTTP (hypertext transfer protocol), FTP (file transfer protocol), SMTP (simple mail transfer protocol), DNS (domain name server), RIP (routing information protocol), SNMP (simple network management protocol) and TELNET (terminal emulation protocol), amongst many others.

All Internet-enabled devices must support TCP/IP version 4 (the current protocol), although most also support version 6 which is expected to become the standard protocol at some point in the future.

Answer 2

A protocol, of which there must be millions of different incompatible ones. Its worse than the languages humans use to communicate (or not) with each other.

Answer 3

Such sets of rules are known as PROTOCOLS.

Answer 4

A protocol