The JWST space observatory consists of a telescope and its four associated scientific instruments, mounted on the telescope itself.

Compared to existing or planned observatories, JWST will have the unique advantage of combining superb image quality, a relatively large field of view and low background light with a highly stable operating environment. All of these are very important characteristics for the infrared observations JWST will need to carry out to see the first stars and galaxies. JWST should operate for at least five years and possibly even for as long as ten.