What does amplitude modulation (AM) primarily alter in a signal?

Amplitude modulation (AM) primarily alters the amplitude of the carrier signal to encode information. In an AM signal, the information signal (such as audio) modifies the height of the carrier wave, allowing variations in loudness or signal intensity to be represented. The frequency and phase of the carrier wave remain consistent; only the amplitude varies to convey the desired information. This technique is commonly used in AM radio broadcasting, where voice or music is transformed into an electrical signal by changing the amplitude of the radio frequency carrier wave. By examining the changes in amplitude, receivers can reconstruct the original signal being transmitted.