How do I self-study String Theory? I am an absolute beginner, with little to no knowledge on the subject but I have somehow developed a strong interest in theories like String theory and M-theory, by reading about them on other forums. So can you   recommend me any farily accessible books or other materials that could help me understand these theories in-depth? Or do I have to extensively study other areas in physics before I am able to comprehend them, if so, what are those other topics?
Introduction to string theory I am in the last year of MSc. and would like to read string theory. I have the Zwiebach Book, but along with it what other advanced book can be followed, which can be a complimentary to Zwiebach. I would like a more mathematically rigorous book or lecture notes along with Zwiebach.   Specifically, mention whether the book discusses string theory   Rigorously? Intuitively?   What's the scope of the book? Does it cover the advanced materials, e.g. Matrix string theory, F-theory, string field theory, etc. Maybe even String Phenomenology?
Intuitive meaning of Globally Hyperbolic I am been studying differential geometry and spacetime and I keep coming across the term . I am having a hard time coming up with an intuitive understanding of this idea. What is an intuitive meaning of globally hyperbolic.  My background is mostly mathematics at a higher undergraduate level.