Bose Einstein Condensate (BEC) is the fifth state of matter in condensed matter
physics. It is the most impressive example of quantum behaviour on a macroscopic scale but
the most difficult state to observe. When low-density boson gas is cooled to a temperature
nearly absolute zero, then BEC is formed. In this condition, the bosons have almost no free
energy to move relative to each other. They clump together, come into the lowest quantum
state, and behave as a single atom. Then microscopic quantum mechanical phenomena work on
a macroscopic scale. This chapter summarizes the history and the developments regarding BEC
with a brief discussion of the key scientists in this field. In the next section, the summary of the
all chapters is given
Keywords: Bose Einstein Condensate, History of Bose Einstein Condensation, Exciton, Polariton.
