Introduction: Stem cells have an interesting history, it traces from mid of 1800 to the date, and it remains the most controversial issue of research even today. The ability of stem cells to self-renew and give rise to generations with variable degrees of differentiation capacities, offers significant potential for generation of tissues that can replace diseased and damaged ones. Aim of the work: Aim of this essay to clarify different types and sources of stem cells and their potential uses to treat many diseases. Conclusion: The potency of the stem cell specifies the differentiation potential and is an important factor that is responsible for the characteristic nature of the stem cells because of this tissue renewing capacity, stem cell researches are now one of the important cornerstones for medical research and development.