What's the difference between Indians, Red Indians and American Indians?

Indians are from India. "Red Indians" is a term many native Americans consider offensive. "American Indians" are the descendants of people who lived in the New World before Columbus arrived there.

The inhabitants of India are called Indians. There the term really does apply. In the New World, however, the only reason people still refer to the natives as "Indians" was because Columbus and Cabot made a mistake in figuring out where they were.

The term arose, I believe, from early European efforts to reach India by sailing west. When they came across the American continent, they thought they had reached India, and the name for the inhabitants unfortunately stuck.