A stem cell is a unique type of cell that has the ability to develop into many different cell types in the body. They are essential for growth, development, and healing. Stem cells can be classified into two main types: embryonic stem cells, which come from early-stage embryos, and adult stem cells, which are found in various tissues throughout the body. Stem cells have the potential to regenerate damaged tissues and organs, making them a focus of medical research. Scientists are exploring their use in treating conditions like Parkinson's disease, diabetes, and injuries, as they may help repair or replace damaged cells and improve health outcomes.