We can categorize computer in some time according to speed of the computer. and some times we can measure this speed by "clock Speed" unit. and we can use "Hertz - Hz" for measure the speed of the computer. and today we are using Gigahertz (Ghz) and Megahertz (Mhz) for measure the speed of modern computers.
And we can use "Bits" to measure the capacity of Central processing Unite and we can cold "word Size" of the computer.
Intel and AMD are very popular Company's about the Processor.