  This is a survey article on the stable cohomotopy refinement of
Seiberg-Witten invariants containing also new results, for example:
  - Stable cohomotopy groups describe path components of certain mapping
spaces.
  - Relation of stable cohomotopy invariants to Seiberg-Witten invariants
without restriction on Betti numbers.
  - Theorem on connected sums along (-2)-spheres.
