Both, depending on application. Most house hold appliances are 120 v. some larger appliances, like Cloths Dryers, air conditioner, heaters or larger hot water heaters can use 220v. normal everyday house current is 120V. Appliances using 220v should have a special plug on them so they cant be used in the wrong plug socket to avoid plugging into the wrong circuit.

Most houses are wired 220 , but wall outlets are 110/120 ...the ovens, stove tops, clothes dryers, Air conditioning...are 220/240...

Mostly 120. 220 is available for larger appliances or heavy machines, like a clothes drier or Hobart mixer.

All wall power is 120v. 220v is used as well, but only for appliances that use heat such as stoves, dryers, water heater, sauna heater, etc.