  We describe the plans for gravitational-wave observations and astrophysics
that will be carried out by the LIGO Scientific Collaboration (LSC) in the next
decade using data from the LIGO Observatories in the US, and sister facilities
abroad in Europe, Japan and India. We provide an overview of gravitational wave
signal types that we are targeting, and the role of gravitational waves in
time-domain multi-messenger astronomy. We briefly summarize what we can infer
from the properties of detected signals, including astrophysical event rates
and populations, tests of gravitational-wave properties, highly-dynamical and
strong-field tests of General Relativity, probing matter under extreme
conditions in neutron stars, and making cosmological measurements with
gravitational-wave sources.
