The second superstring revolution was the intense wave of breakthroughs in string theory that took place approximately between 1994 and 1997.

The different versions of superstring theory were unified, as long hoped, by new equivalences. These are known as S-duality, T-duality, U-duality, mirror symmetry, and conifold transitions. The different theories of strings were also connected to a new 11-dimensional theory called M-theory.

New objects called branes were discovered as inevitable ingredients of string theory. Their analysis - especially the analysis of a special type of branes called D-branes - led to the AdS/CFT correspondence, the microscopic understanding of the thermodynamic properties of black holes, and many other developments.

See also: first superstring revolution