How does the Ghz for a computer processor affect the computer's speed?

Basically, I'm asking how much of a computer's speed relies on the Ghz of the processor? Also, how does that change with different types of processors? To what extent would you take into consideration the Ghz of the processor when purchasing a computer?
How does the Ghz for a computer processor affect the computer's speed?
The more Ghz the better. When buying a computer you should always get the one with the faster processor, but you have to look at other specs too - how much ram a pc has can also affect its speed - the more the better, what kind of video card it has and other things like that. Don't worry about real fast processors unless your into gaming and 2.0 - 2.4 intel or amd will do the job if your into regular everyday web surfing and emailing, but if your a gamer go for 2.4 or faster dual core processor

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