Historically, about 500 distinct Native languages were spoken in North America. The names Native Americans and American Indians are used interchangeably on this website to describe America's first inhabitants.
In many cases "Indians" is a proper name or title such as in "American Indian Movement" or "Bureau of Indian Affairs". The name Indian was used traditionally in American culture and history. The term "Native American" became popular much later but both are commonly used today and neither should be considered preferable over the other, although people do have personal preferences.