  In the past decade, the importance of dissipation and fluctuation to
inflationary dynamics has been realized and has led to a new picture of
inflation called warm inflation. Although these phenomena are common to
condensed matter systems, for inflation models their importance has only
recently started to be appreciated. The article describes the motivation for
these phenomenon during inflation and then examines their origins from first
principles quantum field theory treatments of inflation models. Cosmology today
is a data intensive field and this is driving theory to greater precision and
predictability. This opens the possibility to consider tests for detecting
observational signatures of dissipative processes, which will be discussed. In
addition it will be discussed how particle physics and cosmology are now
working in tandem to push the boundaries of our knowledge about fundamental
physics.
