The amino acids L-glutamate and L-aspartate are the major excitatory neurotransmitters in the mammalian central nervous system (CNS). Some subtleties aside, glutamate is considered the predominant excitatory neurotransmitter and for simplicity the receptors that bind excitatory amino acids will be referred to as glutamate receptors, or GluRs. Glutamate mediates its effects by interacting with receptors that can be distinguished by pharmacological, physiological, anatomical, molecular, and genetic criteria. The interaction of glutamate with its receptors underlies many normal physiological processes, from rapid synaptic signaling and information transfer to longer-lasting changes in synaptic efficacy that are thought to be the cellular basis of learning and memory. In addition, neurotransmission mediated by glutamate and its receptors is implicated in a variety of CNS pathologies, including epilepsy, cell death due to excitotoxicity and ischemia, and Alzheimer's disease. This entry will review the general characteristics...