Avionics

Avionics (aviation + electronics) is the collective term for all electronic systems used in aircraft. Modern avionics include:

Flight instruments and displays (EFIS, PFD, ND)
Communication systems (VHF, HF, SATCOM)
Navigation systems (GPS, VOR, ILS, FMS)
Surveillance (transponder, ADS-B, TCAS)
Flight recorders (FDR, CVR)
Weather radar
Autopilot and flight management
Engine monitoring (EICAS, ECAM)

Avionics can account for 30-40% of a modern aircraft total cost.