While such interfaces as Ethernet , FireWire , and USB all send data as a serial stream , the term `` serial port '' usually identifies hardware meeting the requirements of the RS-232 standard , for the purpose of interfacing with a modem or with a similar communication device . While such interfaces as Ethernet , FireWire , and USB all send data as a serial stream , the term `` serial port '' usually identifies hardware more or less compliant to the RS-232 standard , intended to interface with a modem or with a similar communication device .