Power over Ethernet - or short 'PoE' - allows you to supply DC power for another device over the ethernet network cable. The most common Power Source Equipment (PSE) types are switches and routers (endspan), but you could just as well put a PoE-injector (midspan) between a standard switch and the Powered Device (PD). Especially in corporate environments, PoE devices are growing in popularity, and just to list some examples of PDs: VoIP hardware, wireless access points, access control terminal...
