Cardiovascular diseases are the primary cause of death in the world. Pharmacological and surgical approaches are the main treatment options for heart disease; however, heart transplantation may be the only option for advanced heart failure patients despite its limited nature. Recent advances enabled stem cell-based therapies to become a promising treatment approach for injured or weakened cardiac tissue. With the identification of resident and heart-specific stem cells in early 2000, new avenues of research have been opened to understand heart development, disease, and regeneration. In this review article, different cardiac stem cell subpopulations are classified and defined based on the expression of various characteristic surface or intracellular proteins, including, but not limited to, C-kit, Sca-1, Isl-1, Nkx2.5, HCN4, SIRPA, Flt-1, and KDR. Understanding cardiac stem cell biology, self-renewal, and differentiation mechanisms holds great promise for directing these processes and utilizing these cells to repair or even build new hearts.