RS-485 interface and protocol: What is that ?

 RS485 interface/protocol
   If we should to describe RS-485 protocol as short as possible it is simple serial communication protocol with 2 wires (4 wires for full-duplex) hardware interface, but powerful.   Digital communications networks implementing the EIA-485 standard can be used effectively over long distances and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear,multi-drop configuration.  The standard has not defined a specific communications protocol. The standard UART (RS232) protocol is sometimes used. Most applications define a unique protocol.

As You can see below on the chart we may use this interface, when we need a long cable and/or when we need to connect devices in simple and cheap , but at the time save and stable  industrial or home network.