How do I tell what cpu my computer has?

After 2000s, Intel's competitor, AMD, started using model numbers instead of clock rates to market its CPUs, dispelling the "megahertz myth" which it claimed did not tell the whole story of the power of its CPUs. In 2004, Intel announced it would do the same, probably because of consumer confusion over its Pentium M mobile CPU, which reportedly ran at about half the clock rate of the roughly equivalent Pentium 4 CPU.