When processor chips are manufactured, test circuitry is added to the silicon wafer to determine the maximum speed each processor can operate without malfunctioning. Some processors will not work at the speed to which they are designed, but rather than throwing them away, they are sold as slightly slower chips at a speed which they do work correctly. Since clock speeds come in increments of 100 MHz, you may be able to overclock your chip by less than 100 MHz without a problem, but in general, overclocking is not a good idea.
The faster the clock speed, the more heat the chip generates. You could overclock your chip significantly if you create a more efficient way for the heat to dissipate, like water-cooling your chip. There is a YouTube channel called "Linus Tech" or something where the guy often does this. For me, I would rather just pay the extra money to get a faster processor that is guaranteed (that is, tested) to work.
Also, there are many, many others things about computer hardware and software that most people do not know.