Recent advancement in short pulse laser technology has opened up new possibilities for exciting phenomena and their applications in different fields. Self-focusing is one of the phenomena arises during laser-plasma interaction. Self-focusing has been an active area of scientific study for last few decades. Self-focusing of laser beam in plasma plays an important role in increasing the intensity of laser beam in plasma. The book first introduces the self-focusing and its types. This book presents a comprehensive treatment of self-focusing in collisional plasma and reviews theoretical investigations of self-focusing in collisional plasma.