Stem cell therapy has become a promising and advanced scientific research topic in recent years. This review discusses the discovery of different stem cells and their potential therapies. Stem cells can differentiate into any cell type and have the ability to self-renew. They exist in both embryos and adult cells. Stem cells are classified into totipotent, pluripotent, multipotent, oligopotent, and unipotent cells. Totipotent cells can form all cells of the organism, while pluripotent cells can form cells of all germ layers but not extraembryonic structures. Multipotent cells can differentiate into a narrow range of cell types, while oligopotent cells can differentiate into several cell types. Unipotent cells can only form one cell type. Stem cells play a crucial role in regenerative medicine. They can be used to treat various diseases, including spinal cord injury, heart failure, retinal and macular degeneration, tendon ruptures, and diabetes type 1. Stem cells can also be used in tissue engineering and drug testing. The use of induced pluripotent stem cells (iPSCs) has revolutionized stem cell research, as they can be generated from somatic cells and function similarly to embryonic stem cells. iPSCs have the potential to be used in personalized medicine and regenerative medicine. However, stem cell therapy faces several challenges, including ethical concerns, the risk of teratoma formation, and the need for quality control. The use of iPSCs in therapy requires careful monitoring to ensure their safety and effectiveness. Stem cells have the potential to become a turning point in modern medicine, providing hope for untreatable diseases. The future of stem cell therapy depends on overcoming these challenges and developing safe and effective therapies.Stem cell therapy has become a promising and advanced scientific research topic in recent years. This review discusses the discovery of different stem cells and their potential therapies. Stem cells can differentiate into any cell type and have the ability to self-renew. They exist in both embryos and adult cells. Stem cells are classified into totipotent, pluripotent, multipotent, oligopotent, and unipotent cells. Totipotent cells can form all cells of the organism, while pluripotent cells can form cells of all germ layers but not extraembryonic structures. Multipotent cells can differentiate into a narrow range of cell types, while oligopotent cells can differentiate into several cell types. Unipotent cells can only form one cell type. Stem cells play a crucial role in regenerative medicine. They can be used to treat various diseases, including spinal cord injury, heart failure, retinal and macular degeneration, tendon ruptures, and diabetes type 1. Stem cells can also be used in tissue engineering and drug testing. The use of induced pluripotent stem cells (iPSCs) has revolutionized stem cell research, as they can be generated from somatic cells and function similarly to embryonic stem cells. iPSCs have the potential to be used in personalized medicine and regenerative medicine. However, stem cell therapy faces several challenges, including ethical concerns, the risk of teratoma formation, and the need for quality control. The use of iPSCs in therapy requires careful monitoring to ensure their safety and effectiveness. Stem cells have the potential to become a turning point in modern medicine, providing hope for untreatable diseases. The future of stem cell therapy depends on overcoming these challenges and developing safe and effective therapies.