  The recently commissioned 3.6-m Devasthal optical telescope has been used for
various tests and science observations using three main instruments, namely, a
charge-coupled device camera, a near-infrared camera, and an optical
imager-cum-spectrograph. The published results from these instruments assert
that the performance of the telescope at the Devasthal site is at par with the
expectations. These back-end instruments open up vast opportunities for
high-sensitivity observations of the celestial sky with the telescope. This
paper provides a summary of the existing back-end instruments and attempts to
highlight the importance of the Devasthal optical telescope in synergy with
other telescopes operating at different wavelengths.
