Origins of the ALMA Project in the scientific visions of the North American, European, and Japanese astronomical communities

ALMA is a worldwide project, the synthesis of early visions of astronomers in its three partner communities, Europe, North America, and Japan. The evolution of these concepts and their eventual merger into ALMA are discussed, setting the background for the papers which follow on the scientific requirements and expected performance of ALMA for extra-galactic, galactic, and solar system research.