One kHz or kilohertz is a measurement of frequency equal to 1,000 Hertz. Kilohertz is the unit of measurement for the measurement of alternating current, audio signals and wireless signals.
With circuits, an oscillator circuit supplies a small amount of electricity to a crystal every second, measured in kHz, MHz, or GHz. “Hz” stands for Hertz and “k” stands for Kilos (thousands), “M” for Mega (millions) and “G” for Giga (millions for thousand).
The first CPUs (central processing units) operated at speeds measured in kHz. For example, the first processor, the Intel 4004, ran at 740 kHz. Later processors operating at MHz were available at speeds of 60 MHz to 300 MHz, for example the Intel Pentium processor.
Today's processors run at GHz. When measuring the speed of a processor, the higher the speed (the larger the number), the faster it can run.