This article serves as a primer for the theory of online meaning construction known alternately as conceptual blending, conceptual integration, the many space model, and the network theory. Our tutorial proceeds by analyzing novel and conventional examples of linguistic and nonlinguistic blends that pertain to topics of reference, partitioning, mapping, structure projection, and dynamic mental simulation. Principal concepts and processes of blending theory are described, including composition, completion, elaboration, emergent structure, and optimality constraints. We review recent work on blending theory from the perspective of linguistics, psychology, computer science, and neurobiology, and conclude with a discussion of potential weaknesses of the theory. (Seana Coulson and Todd Oakley)