Interesting diagram of a personal learning network offered by David Delgado. He writes, in the explanation, "the learner chooses their own personal learning environment, taking whatever tools that help them to achieve their own goals. Different people have different ideas to build their own PLE." Quite so, and this is an important thing to keep in mind. The PLE, though it may seem sometimes to be described as though iot were an application, is in fact a suite of tools - and one that may vary for each user. If I talk about 'building a PLE application' (as I do from time to time) I am talking about building an application that can be either one of those tools, or a tool that helps me manage those tools. The main point here is (a) no one tool is 'the PLE', and (b) the main thing about a PLE is that the tools can communicate with each other. Harold Jarche draws on this and compares the idea to Mark Federman's Valence Theory of Organization: "An organization is thus defined as that complex, emergent entity which occurs when two or more people, or two or more organizations, or both, share multiple valences at various strengths, with various pervasiveness, among the component elements." Just so a PLE.