Stem cells can self-renew and differentiate into multiple different cell types. Engineering of stem cells has enabled new methods to study development and organogenesis in humans as well as develop new disease models and therapies. Stem cells can be obtained from multiple sources in vivo or generated in the lab. Engineering of pluripotent stem cells, for example, can potentially generate any tissue in the body and can be used for tissue repair or organoid formation. Furthermore, advances in gene editing technologies have enabled precise editing of stem cell genomes, creating possibilities for establishment of models for diseases and personalized therapies. In this lecture I will discuss the sources and properties of various stem cells as well as their utilization in modelling, therapy and tissue engineering.