Memories provide a link between the present and the past and allow us to project our thoughts into the future. But memories are not immutable; instead, they continually evolve throughout their lifetime, embarking on a dynamic journey the moment they are born. Recent Neuroscience research has provided important new insights into how memories change in time, the mechanisms by which these changes come about and about the nature of the underlying neural representations, sometimes offering promises for the treatment of memory disorders. Nature Neurosciencepresents a focus on memory, comprising Commentaries, Reviews and Perspectives discussing some of the most exciting recent developments and emerging ideas in our understanding of the neurobiology of learning and memory.