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Because of the inferior sound quality of AM broadcasting, the medium lends itself particularly to talk radio, while music radio has in recent decades tended to be broadcast using FM.

AM radio technology is simpler than other types of radio, such as FM radio and DAB. An AM receiver detects the power of the radio wave and amplifies changes in the power measurement to drive a speaker or earphones. The earliest crystal radio receivers used this principle.

AM radio was used for small-scale voice and music broadcasts before World War I. The great increase in the use of AM radio came the following decade. The first commercial radio services began on AM in the 1920s. Radio programming boomed during the " Golden Age of Radio" (1920s to 1950s). Dramas, comedy and all other forms of entertainment were produced, as well as broadcasts of news and music.

AM radio is broadcast in on several frequency bands:

• Long waveLongwave radio frequencies are those below 500 kHz, which correspond to wavelengths longer than 600 meters. They have the property of following the curvature of the earth, making them ideal for continuous, continental communications. Unlike shortwave radi is 144 - 351 kHzHertz is also the name of a car rental company. See The Hertz Corporation''. The hertz (symbol Hz is the SI unit of frequency. It is named in honour of the German physicist Heinrich Rudolf Hertz who made some important contributions to science in the fiel
• Medium waveMediumwave radio transmissions are those between the frequencies of 300 kHz and 3000 kHz. In most of the world, mediumwave serves as the most common band for broadcasting. The standard AM broadcast band is 535kHz to 1705kHz in North America, but remains o is 530 - 1,700 kHz.
• Short waveShortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly in use at tha is 1,700 - 30,000 kHz, divided into 14/15 "broadcast bands".

(In the USThe United States of America also referred to as the United States U. America ¹ or the States is a federal republic in central North America, stretching from the Atlantic in the east to the Pacific Ocean in the west. It shares land borders with Canada in, the allocation of these bands is managed by the FCCThe Federal Communications Commission (FCC) is an independent United States government agency, created, directed, and empowered by Congressional statute. The FCC was established by the Communications Act of 1934 as the successor to the Federal Radio Commi.)

Medium wave is by far the most used for commercial radio broadcasting; this is the "AM radio" that most people are familiar with.

Long wave is used in Europe, Africa, Asia, and Australasia ( ITU regionThe International Telecommunication Union (ITU), in its International Radio Regulations, divides the world into three ITU regions for the purposes of managing the global radio spectrum. Region 1 comprises Europe, Africa, the Middle East west of the Persias 1 and 3). In the Americas, however, this band is reserved for aeronautical navigation .

Short wave is used by radio services intended to be heard at great distances away from the transmitting station; the far range of short wave broadcasts comes at the expense of lower audio fidelity. The mode of propagation for short wave is different, see High frequencyHigh frequency (HF radio frequencies are between 3 and 30 MHz. This range is often called shortwave. Since the ionosphere often reflects HF radio waves quite well, this range is extensively used for medium and long range terrestrial radio communication.. AM is used mostly for broadcast uses – other shortwave users may use a modified version of AM such as SSB or an AM-compatible version of SSB such as SSB with carrier reinserted.

Frequencies between the broadcast bands are used for other forms of radio communication, such as baby monitors, walkie talkies, cordless telephones, radio control, amateur radio, etc.

Medium wave and short wave radio signals act in different ways during daytime and nighttime. During the day, AM signals travel by groundwave, refracting around the curve of the earth over a distance of rarely more than 162 kilometres (100 miles) from the signal's transmitter. However, after sunset, changes in the ionosphere cause AM signals to travel by skywave, enabling many AM radio stations to be heard much farther from their point of origin than is normal during the day. This phenomenon can be easily observed by scanning an AM radio dial at night. As a result, many broadcast stations are required as a condition of license to reduce their broadcasting power significantly after sunset, or even to suspend broadcasting entirely during nighttime hours.

These signals can also be easily disrupted in large urban centres by skyscrapers and other sources of radio frequency (RF) interference.