A gigahertz (GHz) is a unit of frequency that equals one billion hertz. It measures how many cycles per second a signal or wave completes. In electronics, gigahertz is commonly used to describe the clock speed of processors in computers and smartphones, indicating how quickly they can process information. For example, a processor running at 3 GHz can perform three billion cycles per second. Higher gigahertz values typically mean faster performance, but other factors, such as the number of cores and architecture, also influence overall speed. Devices like smartphones and laptops often advertise their processing power in gigahertz.