The heart is the first organ to form and function in the developing embryo. Heart formation is a highly complicated process involving the interaction of various genes at molecular level.During the numerous stages of heart development there may be a number of signaling errors that can occur and lead to congenital heart defects (CHD). Approximately 1 % of the newborns are affected by abnormalities in heart formation, making it the most common form of human birth defects. In this book we explore the role of TBX5 which is known to play a crucial role in the development of heart. This book is intended for anyone inquisitive regarding the process of heart development and brave enough to dive in the deep mystery of processes involved in heart formation.