The NASA/ESA/CSA James Webb Space Telescope is widely referred to as the successor to the NASA/ESA Hubble Space Telescope. In reality, it is the successor to a lot more than that. With the inclusion of the Mid-InfraRed Instrument (MIRI), Webb also became a successor to infrared space telescopes such as ESA's Infrared Space Observatory (ISO) and NASA's Spitzer Space Telescope.