A stem cell is a cell which can produce itself as well as many different differentiated cells. A pluripotent stem cell can produce all the cells of the embryo. For a long time, it was believed that once differentiated a cell cannot be made pluripotent again. In 2006, it was shown that any cell can be made by inserting four transcription factors. By 2012, even entire mouse embryos could be generated by iPSCs. Nowadays the iPSCs are being used to form organoids to understand the cellular function in 3D. The uses of iPSCs are numerous they are increasingly being used in drug discovery, organ transplantation, bioengineering, wound healing, curing cancer etc.