https://www.icts.res.in
String theory: a framework for quantum gravity and various applications - International Centre for Theoretical Sciences
String theory is primarily aimed at unifying quantum field theory and general relativity. Moreover, the invention of the notion of gauge/gravity duality has opened the door for a deep understanding of the relation between these two theories.
Thank you so much for reading. I shall be adding more online resources, notes and videos of multiple disciplines of theoretical sciences in the threads. Keep learning.