Heart diseases are conditions that all physicians, particularly emergency and primary care physicians, frequently encounter and can be considered life-threatening in terms of health issues. This work contains the fundamental information that should be known in the field of cardiology in this regard. Designed as a textbook for training interns, it also serves as a reference book for young physicians in routine practice after graduation, focusing on the early diagnosis and treatment of heart diseases. Essential information about the diagnosis and treatment of common diseases in cardiology is presented in a simple and understandable language. The course topics and scope of this book, which holds a privileged place in its field, have been prepared in accordance with the “National Core Education Program 2020.” While creating the content of the work, recommendations from current cardiology guidelines were taken into account, in addition to clear and accessible sources.