Microprocessor(aka CPU) frequency (clock rate) specifies the operating (internal) frequency of CPU's core. The higher the frequency is for a given CPU family, the faster the processor is. Processor frequency is not the only parameter that affects system performance. Another parameter that greatly affects the performance is CPU efficiency, that is how many Instructions Per Clock (IPC) the CPU can process. Knowing these two parameters it's easy to calculate total number of instructions per second that can be processed by CPU: Frequency x IPC. All modern Microprocessors(AMD x86,Intel microprocessors based P6, mobile and Core micro-architectures) tried to improve their performance by improving the IPC, and, whenever possible, by increasing processor frequency.
The CPU frequency(used as Processor's speed indicator ) is measured in