Remarkably, many expectations as to how the imprinting mechanism works have bees confounded by these studies As a result, the time now seems right to reconsider our current understandings of the nature of imprinting, and how best it can be defined. Here, I discuss the past and present understanding of imprinting in the light of results obtained from studies of endogenous imprinted genes, and finally propose that tbe current multiplicity of imprinting terms and definitions be replaced by a single term and definition.