The measure of resistance in a circuit to the flow of an electric current. The greater the ohm value the more difficult it is for current to flow through a given circuit. Conversely, a low ohm value represents a low resistance and the easy flow of current through a circuit. hms are often used in reference to loudspeakers which have a certain level of resistance associated with them. A typical speaker may have an ohm rating (rating the speaker’s resistance) of 4 to 8 ohms nominal impedance (impedance being resistance to current flow). Resistance in a speaker varies, however, from low ranges often as low as 2 or 3 ohms to high ranges as high as 30 or more ohms. s speaker impedance decreases, more current flows and the amplifier is called upon to output more power to the speaker. When shopping for speakers and amplifiers, make sure the amplifier is able to output power properly into the speakers’ impedance. Many receivers are not able to operate properly with speakers having impedance loads of less than 8 ohms. While most separate amplifiers can handle lower impedance loads down to 4 ohms or less, some speakers present impedances of 1 or 2 ohms at their minimum requiring particularly robust and powerful amplifiers designed for such loads. Generally, most any separate amplifier will be able to properly power almost any speaker (with the few exceptions being in most cases highly-exotic, very expensive speaker designs) while receivers should be mated with speakers having nominal impedances (average impedances) of around 8 ohms.