The Extreme-ultraviolet Imaging Telescope (EIT) is a key instrument on the SOHO mission, designed to provide wide-field images of the solar corona and transition region up to 1.5 solar radii above the solar limb. The telescope uses multilayer-coated optics to select spectral emission lines from Fe IX (171 Å), Fe XII (195 Å), Fe XV (284 Å), and He II (304 Å), allowing for sensitive temperature diagnostics in the range from 6 × 10^4 K to 3 × 10^6 K. The EIT has a 45×45 arcmin field of view and a spatial resolution of approximately 5-arcsec, enabling global-scale observations of coronal plasma and underlying cooler, turbulent atmospheres. The paper details the EIT's instrumentation, performance, and operating modes, including its multilayer optics, CCD image sensor, and data processing capabilities. The EIT's primary scientific objective is to study the dynamics and evolution of coronal structures over various time scales, sizes, and temperatures, providing insights into coronal heating and solar wind acceleration. The EIT's observations will complement those from other SOHO instruments and ground-based observations, enhancing our understanding of solar phenomena.The Extreme-ultraviolet Imaging Telescope (EIT) is a key instrument on the SOHO mission, designed to provide wide-field images of the solar corona and transition region up to 1.5 solar radii above the solar limb. The telescope uses multilayer-coated optics to select spectral emission lines from Fe IX (171 Å), Fe XII (195 Å), Fe XV (284 Å), and He II (304 Å), allowing for sensitive temperature diagnostics in the range from 6 × 10^4 K to 3 × 10^6 K. The EIT has a 45×45 arcmin field of view and a spatial resolution of approximately 5-arcsec, enabling global-scale observations of coronal plasma and underlying cooler, turbulent atmospheres. The paper details the EIT's instrumentation, performance, and operating modes, including its multilayer optics, CCD image sensor, and data processing capabilities. The EIT's primary scientific objective is to study the dynamics and evolution of coronal structures over various time scales, sizes, and temperatures, providing insights into coronal heating and solar wind acceleration. The EIT's observations will complement those from other SOHO instruments and ground-based observations, enhancing our understanding of solar phenomena.