Modulation is a process in telecommunications where periodic waveforms are modified so they will vary from one another. A waveform characterizes the shape and form of a specific signal. When waveforms are given certain variations, a particular message is conveyed.

Modulation can be compared to the process in which an individual would modify the sound of a musical instrument. In this case, the tone of the instrument can be considered as the waveforms.

Modulation consists of several components and parameters. The waveform used in modulation is usually a high-frequency sinusoid. A sinusoid is a function describing a wave-like property of time. These sinusoids are used as carrier signals in modulation.

The carrier signals in modulation have three main parameters: amplitude, phase, and frequency.

Amplitude refers to the amount of change in the signal.

Phase is the fraction of a full cycle which corresponds to an offset. This offset is found within a displacement from a particular reference point at a given time.

Frequency is the measurement of the number of occurrences of an event within a period of time.

To obtain the modulated signal, all of the three parameters are modified using a low frequency information signal as the reference point.

The concept of modulation has inspired the development of certain devices. Modulators, for instance, perform the process of modulation while demodulators do the inverse structure of the said process. A device that can do both modulation and demodulation is called a modem, widely used for Internet purposes. Other common devices that apply the concept of modulation include AM and FM radios.