  Warm inflation is an inflationary scenario in which a thermal bath coexists
with the inflaton during inflation. This is unlike standard cold inflation in
which the Universe is effectively devoid of particles during inflation. The
thermal bath in warm inflation is maintained by the dissipation of the
inflaton's energy through its couplings to other fields. Many models of warm
inflation have been proposed and their predictions have been compared with
cosmological data. Certain models of inflation that are disallowed in the
context of cold inflation by the data are allowed in the warm inflationary
scenario, and vice versa.
