What is the difference between "megahertz" and "gigahertz"?

What is the difference between "megahertz" and "gigahertz"?

Ali Nasri (Computer Specialist, Mac 911 Inc.) gives expert video advice on: How does cache affect the speed of my computer? and more...

A megahertz and a gigahertz are used to determine the speed of the computer. The faster the megahertz or gigahertz, the faster your computer is going to be. Computers nowadays are all measured in gigahertz. Megahertz is from the past. A gigahertz is equal to a billion cycles per second. A megahertz is a million cycles per second.