What is the specific meaning of the American Revolution?

Although the British Empire continued to expand during the 18th and 19th centuries, the American colonies, by breaking away, became the first areas under British control to leave the empire and establish their own political entity.  This process continued for many countries under British rule, even into our own day, and although politically independent, became known as "Commonwealth Countries."

The American Revolution also inspired much of Central and South America, most of which was under Spanish control,  to break away from Spain.  Up until the 1830's various former Spanish colonies became their own countries.

Finally, the Americans, having thrown off what they perceived to be an unjust governance, inspired the French to do the same in the French Revolution a few years later. The main difference here was  that the changes took place within the mother country and not within far flung colonies.