  A neutron star low-mass X-ray binary is a binary stellar system with a
neutron star and a low-mass companion star rotating around each other. In this
system the neutron star accretes mass from the companion, and as this matter
falls into the deep potential well of the neutron star, the gravitational
potential energy is released primarily in the X-ray wavelengths. Such a source
was first discovered in X-rays in 1962, and this discovery formally gave birth
to the "X-ray astronomy". In the subsequent decades, our knowledge of these
sources has increased enormously by the observations with several X-ray space
missions. Here we give a brief overview of our current understanding of the
X-ray observational aspects of these systems.
