Eilenberg-MacLane 1945 spaces: pi_n(K(G,n)) iso G, all other homotopy groups trivial; classify ordinary cohomology functorially [X, K(G,n)] iso H^n(X;G).
Eilenberg-MacLane 1945 spaces: pi_n(K(G,n)) iso G, all other homotopy groups trivial; classify ordinary cohomology functorially [X, K(G,n)] iso H^n(X;G).