The EVE instrument is designed to measure the solar extreme ultraviolet (EUV) irradiance. The EUV radiation provides the majority of the energy for heating Earth’s thermosphere and creating Earth’s ionosphere (charged plasma). This wide spectral range requires the use of multiple channels. Some key requirements for EVE are to measure the solar EUV irradiance spectrum with 0.1 nm spectral resolution and with 20 sec cadence. These drive the EVE design to include grating spectrographs with array detectors so that all EUV wavelengths can be measured simultaneously. Another key requirement for EVE is to measure the EUV radiation with an accuracy of 25% or better, thus on-board calibration channels are included to go with under flight calibration experiments to be conducted during the SDO mission.