We study how the circuitry of the retina translates the visual scene into electrical impulses in the optic nerve. Visual perception is initiated by the molecules, cells and synapses of the retina, acting together to process and compress visual information into a sequence of spikes in a population of nerve fibers. One of the largest gaps in neuroscience lies in the explaining of systems-level processes like visual processing in terms of cellular-level mechanisms. This problem is tractable in the retina because of its experimental accessibility, and the substantial amount already known about basic retinal cell types and functions.