A multimeter, also known as a Volt-Ohm-Milliameter, is an electronic measuring instrument that is typically used to measure voltage, current, and resistance. There are analog multimeters that operate by moving a pointer to display the measurement, but today most multimeters are digital with an LCD that is used to display exactly what the measurement is.
A multimeter can cost as low as USD $10 and up to USD $400 for a really nice Fluke 87V. Unless you are planning on using the multimeter for professional purposes, I would recommend getting a low-cost multimeter like the ones shown in the following photograph:
The digital multimeter has three main parts, which are the display, selection knob, and the probe ports.
The display will show what the measurement is. Some of the higher-end multimeters have a backlit display to make it easier to read in low light.
The selection...