The work proposed is aimed at a deeper understanding of the basic laws and forces of nature. It is based on string theory and M-theory which are theoretical models which combine quantum mechanics and gravity with the other forces of nature in a unified framework. There are several objectives to this work. One is a better understanding of black holes in the framework of string theory. This part of the proposal involves a detailed comparison between the structure of black holes as solutions to Einstein's theory of general relativity and the description of black holes as configurations of strings and extended objects like membranes. Another part of the proposal studies the properties of extended objects in M-theory. These objects are part of a unification between gravity and the gauge theories which describe elementary particles. The broader impacts are two fold. One central aspect of the work is the training of graduate students and the development of problem solving skills. The second is to integrate research into the undergraduate curriculum.