The purpose of this chapter is to first survey the astronomical situation of cometary ices, as they are known today – their location in the solar system, the discernable nature of the ices from remote sensing measurements, and the important physico-chemical properties of the ice known from previous laboratory studies. We then attempt to synthesize this material into a framework for recognizing the most important unresolved issues in understanding the behavior of low temperature, porous, mixed amorphous/crystalline and radiation damaged ices - with the hope of launching new, important laboratory studies of cometary ice analogues.