Stem cells are primitive cells with the ability to self-renew and differentiate into various cell types. They play a critical role in embryonic development and are also present in adult tissues, where they contribute to regeneration and repair functions to some extent. One of the goals of stem cell research is to harness their properties to treat various diseases and injuries, such as heart disease, stroke, and Parkinson's disease. This application is known as stem cell therapy. Stem cells can be categorized based on their source, differentiation potential, and other factors, including cancer stem cells, embryonic stem cells, germline stem cells, neural stem cells, mesenchymal stem cells, endothelial progenitor cells, hematopoietic progenitor cells, lineage markers, and stem cell cytokines.