  We study a class of early dark energy models which has substantial amount of
dark energy in the early epoch of the universe. We examine the impact of the
early dark energy fluctuations on the growth of structure and the CMB power
spectrum in the linear approximation. Furthermore we investigate the influence
of the interaction between the early dark energy and the dark matter and its
effect on the structure growth and CMB. We finally constrain the early dark
energy model parameters and the coupling between dark sectors by confronting to
different observations.
