  Quasars are the earliest objects known to exist. We examine their origin in
the context of popular models for structure formation in the universe. We show
that seeds for quasar black holes could have originated from the initial
cosmological collapse of overdense regions with unusually small rotation. Most
of these seeds have a mass of order 10^6 solar masses, just above the
cosmological Jeans mass. For Cold Dark Matter cosmologies, we find of order one
seed black hole per bright galaxy. After the galaxy forms, the seeds inside its
bulge sink to the center by dynamical friction. We also describe a few
empirical methods to study the properties of quasars and their environments.
These include: probing quasar hosts through [C II] emission, finding quasar
lifetimes from the ``proximity effect'' along two lines of sight, and measuring
the amplitude of clustering at high redshifts through the detection of
Lyman-alpha clouds beyond the quasar redshift.
