The colonists didn't like taxation without representation. The most famous rebellion was the Boston Tea Party. Our national and state constitutions show that the idea of democracy comes directly from the Magna Carta which was written in 1215. Democracy is a system where people govern themselves by presenting new ideas and making decisions by voting. An alternative to democracy is a dictatorship and people often rebel against that kind of government.
People are more willing to be governed by a government when they have a say in that government.
In a democracy there is a one vote per person rule. Compared to the number of people voting one vote can seem very insignificant. Many people don't vote because they feel their vote won't make a difference. However the can make a difference. A person can make their vote count for even more than one vote by persuading other people vote in favor of what she or he wants.