No-Hair Theorem
The discussion in the left panel is sometimes stated in a very colorful way. One says that "a black hole has no
hair", and black hole theorists refer commonly to the "no-hair theorem".
This is just a picturesque way of saying
that black holes lose all detailed information (the "hair") of the matter that makes them up when they form,
leaving only mass, charge, and angular momentum as distinguishing characteristics.