  A large fraction of X-ray sources in our Galaxy are low-mass X-ray binaries,
containing a black hole or a neutron star accreting from a gravitationally
bound low-mass ($\leq$1 M$_\odot$) companion star. These systems are among the
older population of stars and accreting systems in the Galaxy, and typically
have long accretion histories. Low-mass X-ray binaries are categorized into
various sub-classes based on their observed properties such as X-ray
variability and brightness, nature of the companion star and/or the compact
object, and binary configuration. In this Chapter, we review the phenomenology
of sub-classes of these systems and summarize observational finding regarding
their characteristics, populations, and their distribution in the Galaxy.
