What is the differences between a republic and a democracy?

[giovonni]

Greeting's to all,
I've always wondered why, most U.S. president's and congressional leader's want to spread "democracy," all around the world? Especially, since the U.S. is a republic, and the majority does not necessarily rule. Who knows the differences between a republic and a democracy? Is a democracy, the only true way for a people to govern themselves? giovonni