A multimeter is an instrument used to test and measure alternating current (AC) or direct current (DC) voltage, resistance, and electric current. Multimeters combine voltmeters, ammeters, and ohmmeters. Electricians use multimeters to run diagnostics on batteries, switches, components, power sources, and motors. Multimeters are analyzers used to diagnose electrical problems, find the source of the issue, and make repairs.
Purchase an analog or digital multimeter, depending on the display you prefer. Digital devices feature an LCD display with a decimal reading, while analog multimeters move a bar through a number scale. Choose the one compatible with what components you test most, be it a high-voltage car battery or low-voltage device.