One of the great mysteries of modern cosmology is the origin and nature of dark energy - a smooth component that contributes about 75% of the total energy density in the universe and causes its accelerated expansion. Although discovered just a decade ago, dark energy has recently been confirmed via several independent cosmological probes; nevertheless, there are no good theoretical leads as to its physical provenance. In this talk I examine critically various approaches to measure the macroscopic properties of dark energy, and describe methods to model the expansion history of the universe in the presence of dark energy.

ANL Physics Division Colloquium Schedule