Cardiology, as an independent specialty, is a branch of internal medicine. A cardiologist specialises in the diagnosis and treatment of diseases of the cardiovascular system. This specialty is to be distinguished from the sub-specialty of cardiac surgery. A cardiologist is not the same as a heart surgeon. The latter opens the chest and performs heart surgery. A cardiologist, on the other hand, examines and diagnoses cardiovascular diseases and performs procedures such as cardiac catheterisation or the insertion of a pacemaker.

Of course, every cardiologist is also a specialist in internal medicine and also treats all diseases beyond cardiology.