Many intuitive notions of “learning” do not support the diverse kinds of learning across different situations and learners. In this paper I offer a functional definition of learning from a cognitive science perspective, which attempts to account for the presence of learning in different physical substrates. The definition is that a particular event should be considered a good example of “learning” to the degree to which the following characteristics describe it: 1) a system undergoes change to its informational state or processing 2) the change is for the purpose of more effective future action, 3) the change is in response what the system experiences, and 4) the system executes the change, rather than some outside force. Episodes are better examples of learning according to how many of these characteristics they have. I discuss benefits and limitations of this characterization.