I'm unsure if this is the right place for this question or not but hopefully I'll still get some helpful responses even if I'm in the wrong place! I was discussing a potential string theory research project with a potential supervisor and he was asking me whether I was more interested in "formal aspects" or applied things? To be honest, I don't really know the difference! I assume that formal aspects is essentially studying the theory i.e. the maths behind string theory (so this would be a lot of quantum field theory and group theory for the symmetries etc and hopefully some general relativity as well?) Would applied things be for example, the use of string theory in describing black holes? I guess this would involve more general relativity than the first one? I'd like to do my project in this area but would like as much general relativity as possible - therefore, my questions are: (i) Is my understanding of formal aspects and applied aspects correct? (ii) Which would allow me to use more General Relativity? Thanks very much for your replies!