This expository talk introduces three families of combinatorial objects connecting linear algebra, representation theory, and the geometry of the Grassmannian. Plabic graphs were introduced by Postnikov to index and parametrize positroid cells in the totally nonnegative Grassmannian. Knutson and Tao's honeycombs describe eigenvalues of Hermitian matrices A, B, and A+B; their dual model, hives, give a lattice-point-counting rule for Littlewood-Richardson coefficients. Through small examples, I will explain each construction, and illustrate the correspondence between honeycombs and hives, and their relationships to local moves on plabic graphs. No prior familiarity with the topics will be assumed. This exposition follows a part of Postnikov's talk "Honeycombs, Plabic Graphs, and Polypositroids" from AsiaComb 2026, supplemented by the work of Knutson-Tao-Woodward on hives and the octahedron recurrence.