There are many different kinds of stem cells. I will discuss the most "powerful" ones here. They are called pluripotent stem cells (PSCs). Pluripotent stem cells are the master cells which can basically turn into cell, tissue or organ of the human body (like heart or brain). They also have the power to infinitely self-renew, which means that we can make trillions of copies of them in the lab. Pluripotent stem cells are currently used in research programs in many laboratories across the globe.