Abstract: The universe is currently expanding at an accelerated rate, space itself grows. Gravity, however, always acts as an attractive force and would per se slow down this expansion. General relativity links these dynamics of space to its content: The geometry not only couples to the energy density, but also to the corresponding pressure. To achieve acceleration cosmologists stipulate the existence of a fluid with a negative pressure: dark energy. The measurements that support this notion are supernova measurements, the cosmic microwave background and large-scale structure (LSS) observations. These show that dark energy makes up almost 70% of the total energy budget of the universe. In this work we explore possible candidates for dark energy. We further analyze possible relationships within the dark sector that also includes dark matter, and finally compute the impact of future LSS measurements on the model parameters.