The purpose of an internal combustion engine is to transform chemical energy into mechanical energy. This is accomplished by igniting an air/fuel mixture that causes a shaft to rotate. We then use this rotating shaft to create useful work.
Digital Multi-Meters come in two common varieties: Auto- Ranging, and Non Auto-Ranging. A non auto-ranging meter requires you to select a range of “sensitivity” for the given function you are using. For example if you want to measure resistance, you would need to select a range of up to 200 ohms, up to 20Kohms (20,000 ohms), 200Kohms, etc. An auto-ranging meter will automatically figure out the range and give you a measurement.