quantum mechanics and space and time. In string theory all the forces and particles emerge in an elegant geometrical way, realizing Einstein's dream of building everything from the geometry of space-time. String theory is based on the (deceptively simple) premise that at Planckian scales, where the quantum effects of gravity are strong, particles are actually one-dimensional extended objects. Just as a particle that moves through spacetime sweeps out a curve (the worldline) string will sweep out a surface (the world-sheet) In contrast with particle theories, string theory is highly constrained in the choice of interactions, supersymmetries and gauge groups. In fact, all the usual particles emerge as excitations of the string and the interactions are simply given by the geometric splitting and joining of these strings: In this way the usual Feynman diagrams of quantum field theory are generalized by arbitrary Riemann surfaces Much recent interest has been focused on D-branes. A D-brane is a submanifold of space-time with the property that strings can end or begin on it. More information on the web * Een Nieuwe Revolutie in Stringtheorie, a popular article in Dutch about recent developments, Afleiding 1 (1996) 7-11 (in Dutch, ps-file) * Nonperturbative String Theory, a somewhat more technical review in English of recent developments. * Superstring Theory, by Brian Greene. * String Theory and the Unification of All Forces, by Sunil Mukhi. * The Second Superstring Revolution, by John Schwarz Some recent popular literature on string theory * G. Taubes, A Theory of Everything Takes Shape, Science 269 (1995). * P. Townsend, Unity from Duality, Physics World, Sept 1995. * E. Witten, Reflections on the Fate of Spacetime, Physics Today, April 1996. * M. Mukerjee, Explaining everything, Scientific American, January 1996. Good starting points in the scientific literature * M.B. Green, J.H. Schwarz, E. Witten, Superstring Theory, two volumes (Cambridge University Press, 1987). Still the most complete treatment of the pre-1987 material. * J. Polchinski, What is String Theory? in Les Houches 1994, `Fluctuating Geometries in Statistical Mechanics and Field Theory,' hep-th/9409168. A good review of the material that ends just before the `1994 revolution.' It also includes the matrix models and random surface ideas of 1989/90. * J. Polchinski, Tasi Lectures on D-branes, hep-th/9611050. All you want to know about D-branes, the single most important ingredient to understand non-perturbative string theory. * B. Greene, String Theory on Calabi-Yau Manifolds, hep-th/9702155. A excellent review of (super)conformal field theory, supersymmetric sigma models, mirror symmetry etc. * H. Ooguri, Z. Yin, TASI Lectures on Perturbative String Theory, hep-th/9612254. A compact lecture series that treats the essentials of perturbative string theory in an elegant way. * R. Dijkgraaf, Les Houches Lectures on Fields, Strings and Duality, to be published in Les Houches 1995, `Quantum Symmetries.' hep-th/9703136 My lecture notes on the more mathematical aspects of modern quantum field theory and strings. * T. Banks, Matrix Theory, hep-th/9710231. A review of matrix theory, at this moment the hot topic in string theory. String theory is a still-developing mathematical approach to theoretical physics, whose original building blocks are one-dimensional extended objects called strings. Unlike the point particles in quantum field theories like the standard model of particle physics, strings interact in a way that is almost uniquely specified by mathematical self-consistency, forming an apparently valid quantum theory of gravity. Since its birth as the dual resonance model which described the strongly interacting hadrons as strings, the term string theory has changed to include any of a group of related superstring theories and larger frameworks such as M-theory, which unite them. A shared property of all these theories is the holographic principle. String theorists have not yet completely described these theories, nor have they determined if these theories relate to the physical universe or how.[1] The logical coherence