  The consensus of opinion in cosmology is that the Universe is currently
undergoing a period of accelerated expansion. With current and proposed high
precision experiments it offers the hope of being able to discriminate between
the two competing models that are being suggested to explain the observations,
namely a cosmological constant or a time dependent `Quintessence' model. The
latter suffers from a plethora of scalar field potentials all leading to
similar late time behaviour of the universe, hence to a lack of predictability.
In this paper, we develop a model independent approach which simply involves
parameterizing the dark energy equation of state in terms of known observables.
This allows to analyse the impact dark energy has had on cosmology without the
need to refer to particular scalar field models and opens up the possibility
that future experiments will be able to constrain the dark energy equation of
state in a model independent manner.
