EIT was originally conceived as a viewfinder instrument to help select observing targets for the other instruments on board SOHO, but EIT is credited with a good fraction of the original science to come from SOHO, including the first observations of traveling wave phenomena in the corona, characterization of coronal mass ejection onset, and determination of the structure of coronal holes.
EIT is the first long-duration instrument to use normal incidence multilayer coated optics to image the Sun in extreme ultraviolet.
Conventionally these wavelengths have been reflected either using grazing incidence (as in a Wolter telescope for imaging X-rays) or a diffraction grating (as in the jocularly-termed overlappograph flown on Skylab in the mid-1970s).
Solar imaging with multilayer EUV optics was pioneered in the 1990s by the MSSTA and NIXT sounding rockets, each of which flew on several five-minute missions into space.
The EIT PI, Jean-Pierre Delaboudiniere, was forced to scrounge funding and resources from several locations to construct and launch the instrument.
The TRACE, STEREO, and Proba-2 spacecraft (launched in 1998, 2006, and 2009, respectively) carry similar multilayer imagers, as does the Solar Dynamics Observatory mission.