String theory has been called the 'theory of everything'. It seeks to describe all the fundamental forces of nature. It encompasses gravity and quantum mechanics in one unifying theory. This title presents an introduction to one of the most talked-about areas of physics. "[T]his book is a concise survey of advanced ideas in particle physics and string theory. But it is also true that every single concept is explained in a very simple and accurate way. This makes the book, while without errors from a physicist's point of view, accessible to a wide range of readers."---Farhang Loran, Mathematical Reviews