Edge of knowledge: Tied up with string -- Dilemma of space, time, and the quanta: Space, time, and the eye of the beholder -- Of warps and ripples -- Microscopic weirdness -- Need for a new theory: general relativity vs. quantum mechanics -- Cosmic symphony: Nothing but music: the essentials of superstring theory -- "Super" in superstrings -- More dimensions than meet the eye -- Smoking gun: experimental signatures -- String theory and the fabric of spacetime: Quantum geometry -- Tearing the fabric of space -- Beyond strings: in search of M-theory -- Black holes: a string/M-theory perspective -- Reflections on cosmology -- Unification in the twenty-first century: Prospects.