Clock cycle

A single electronic pulse of a CPU is referred to as a clock cycle, or cycle. A CPU can perform a simple action, such as fetching an instruction, accessing memory, or writing data during each cycle. Because each clock cycle can only perform simple commands, most CPU functions require many clock.

CPU cycle follows to process instructions from boot-up till the computer system shuts down.

Processor speeds are measured in megahertz or gigahertz since current processors may complete millions of clock cycles per second.

How many number of cycles can a CPU perform?

A CPU's clock speed determines how quickly it can process instructions. Hence, CPU with a clock speed of 2 gigahertz (GHz) can carry out two thousand million (or two billion) cycles per second. 

What are wasted CPU cycles?

CPU cycles wasted indicate that the CPU is not performing any work during those cycles.