what is overclocking

i'm a greener in english, especially in terms of computer sicence.
aim to used to these, i have to collect some terms and their definitions. this is another one "overclocking":
Overclocking is making a computer component run at a higher clock speed than the manufacturer's specification. Although there are many different reasons for overclocking, the most popular reason is to increase hardware performance. Overclocking can result in system instability and sometimes even hardware failure if done carelessly.