After a short introduction to the equations of FLRW Cosmology, I review the four main techniques used to understand observationally the properties of dark energy in turn, followed by a short summary of the current understanding of the subject. I finalize with a description of a few of the main dark-energy oriented surveys that are going to take place in the near future.

PACS numbers: 95.36.+x, 98.80.–k, 98.80.Cq