While IoT ecosystem is usually considered to be composed of wireless devices, it is still possible to connect IoT solutions using a wired connection. In this chapter, we do not present communication protocols that are short distant one designed to connect sensors to IoT device, like I2C, SPI, Serial, etc. Those are described in chapter introduction_to_iot_communication_and_protocols.
When wireless-enabled SoCs where about to be delivered to the market (i.e. ESP8266), there were already available sorts of extension devices for popular Embedded systems, like i.e. Ethernet Shield for Arduino boards (figure ##REF:net_ethernet_shields##):

Cooper based wired networks also bring an extra feature to the IoT designers - an ability to power the device via a wired connection, i.e. PoE (Power over Ethernet) - 802.3af, 802.3at, 802.3bt ¹⁾. Long distance connections may be implemented using optic-based, fibre connections, but those require physical medium converters that are usually quite complex, pretty expensive and power consuming thus they apply only to the niche IoT solutions. Please note, mentioned optical connections do not cover so-called LiFi, as those are considered to be wireless ²⁾.

A non exhaustive list of some present and former wired networking solutions are presented in the table 1: