higher geometry / derived geometry
geometric little (∞,1)-toposes
geometric big (∞,1)-toposes
derived smooth geometry
An orbispace is a space, particularly a topological stack, that is locally modeled on the homotopy quotient/action groupoid of a locally compact topological space by a rigid group action.
Orbispaces are to topological spaces what orbifolds are to manifolds.
A detailed but elementary approach via atlases can be found in
and another approach is sketched in
André Henriques, Orbispaces and orbifolds from the point of view of the Borel construction, a new definition (arXiv:0112006)
André Henriques, Vector bundles on orbispaces (2005) (pdf)