What is a James Webb Telescope?

The James Webb Space Telescope (also called JWST or Webb) is a space telescope being built by Nasa in international collaboration with ESA or European Space Agency and CSA or Canadian Space Agency, which will complement and extend the discoveries of the Hubble Space Telescope, with longer wavelength coverage and greatly improved sensitivity. Webb will be a large infrared telescope with a 6.5-meter primary mirror and will be launched on an Ariane 5 rocket from French Guiana in March, 2021. The duration of the mission is between 5-10 years.