Frequency may refer to any of the following:
1. In general, frequency is a measurement of how often something happens. In science and technology, frequency is measured in Hz (hertz).
2. Concerning a CPU (central processing unit), frequency refers to the processor's operational clock cycles per second. The frequency of most modern CPUs is measured in GHz, or billions of cycles per second.
3. A frequency is the number of oscillations in alternating electrical current each second.
4. The term frequency may also refer to cycles per second of an electromagnetic wave, such as a sound wave or a light wave. The frequency of light determines its color, as seen by the human eye. Similarly, the frequency of sound determines its pitch, as heard by the human ear.