Groups are the mathematical object formally describing our intuitive idea of symmetry. For this reason "wherever groups disclose themselves or can be introduced, simplicity crystallizes out of comparative chaos". But how do we study groups? We can focus on their inherent combinatorics or look at their images into groups of matrices. This latter point of view is known as group representation theory. In this seminar I will discuss some important open problems in group representation theory.  I will also discuss the global-local principle by focusing on two of the main global-local conjectures in the area.