Some aspects of descent theory and applications

This thesis is an exposition of the author’s contribution on effective descent morphisms in various categories of generalized categorical structures. It consists of: Chapter 1, where an elementary description of descent theory and the content of each remaining chapter is provided, supplemented with references; Chapter 2, consisting of various descent theoretical definitions and results employed in the remainder of this work; four chapters, each corresponding to an article written by the author during the period of his PhD studies.