  In these lectures, I describe a variety of efforts to identify or constrain
the identity of dark matter by detecting the annihilation or decay products of
these particles, or their effects. After reviewing the motivation for indirect
searches, I discuss what we have learned about dark matter from observations of
gamma rays, cosmic rays and neutrinos, as well as the cosmic microwave
background. Measurements such as these have been used to significantly
constrain a wide range of thermal relic dark matter candidates, in particular
those with masses below a few hundred GeV. I also discuss a number of anomalies
and excesses that have been interpreted as possible signals of dark matter,
including the Galactic Center gamma-ray excess, the cosmic-ray antiproton
excess, the cosmic-ray positron excess, and the 3.5 keV line. These lectures
were originally presented as part of the 2018 Theoretical Advanced Study
Institute (TASI) summer school on "Theory in an Era of Data". Although intended
for advanced graduate students, these lectures may be useful for a wide range
of physicists, astrophysicists and astronomers who wish to get an overview of
the current state of indirect searches for dark matter.
