The James Webb Space Telescope (JWST) is the top priority NASA project for the exploration of the Universe, in partnership with the European Space Agency (ESA) and the Canadian Space Agency (CSA). It is considered the scientific successor of the iconic Hubble Space Telescope, and represents a much improved version of it thanks to its larger primary mirror, its ability to analyse infrared light, and for its sophisticated suit of scientific instruments. For all these reasons, the James Webb will be able to study hitherto unexplored objects, regions and periods in the history of the Universe, and thus make fundamental contributions in many fields of astronomy.  This conference will summarize the main scientific themes of James Webb and Hubble's legacy in some of them, such as the study of the early Universe and the characterization of exoplanets. Likewise, the fundamental characteristics of the telescope and some of the technological challenges that have been necessary to overcome will be described. The European and Spanish participation in the project will also be briefly commented and, finally, the current status of the telescope and the next phases before the start of its scientific operations. 

This conference will summarize the main scientific themes of James Webb and Hubble's legacy in some of them, such as the study of the early Universe and the characterization of exoplanets. Likewise, the fundamental characteristics of the telescope and some of the technological challenges that have been necessary to overcome will be described. The European and Spanish participation in the project will also be briefly commented and, finally, the current status of the telescope and the next phases before the start of its scientific operations.