Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The James Webb Space Telescope (JWST) is a planned infrared space observatory, the partial successor to the aging Hubble Space Telescope. The JWST will not be a complete successor, because it will not be sensitive to all of the light wavelengths that Hubble can see. The main scientific goal is to observe the most distant objects in the universe, those beyond the reach of either ground based instruments or the Hubble. The JWST project is a NASA-led international collaboration with contributors in fifteen nations, the European Space Agency and the Canadian Space Agency.