An iterated fibration of Eilenberg-Mac lane spaces. Every topological space has this homotopy type.
Postnikov System
See also
Eilenberg-Mac Lane Space, Fibration, HomotopyExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Postnikov System." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PostnikovSystem.html