Abstract: Low-mass starless cores are the incipient phase of low-mass star formation. They are observed via submillimeter dust continuum and dense gas molecular lines, they typically contain a few solar masses, they have sizes of approximately 0.1 pc, and they may form one or a few low-mass (M ~ 1 M_sun) stars. It is crucial to understand the formation and evolution of these objects to set the initial conditions for protostar and disk formation. Theoretically, the basic core formation and evolution process is still debated between a turbulent-dominated or ambi-polar diffusion-dominated model. Observationally, a fundamental challenge is to determine the evolutionary state of a starless core. I shall review the basic processes that are used to develop a chemical evolutionary sequence for low-mass starless cores and that breaks currently observed degeneracies in thephysical structure of the cores. I shall highlight results from the Arizona Radio Observatory-Green Bank Telescope Survey which has mapped a sample of 25 nearby starless cores in dust continuum emission and 10 molecular transitions.