Through this brief introduction to the world of stem cells, Sara Reynoso Fuentes describes their medical applications in the context of cancer. Sara is a 16-year-old Mexican student of the International Baccalaureate program. She immigrated to Zurich from her home country at the age of 9 and has been living there ever since. She has been fortunate enough to be able to enjoy a mixture of things, from literature and theatre, to questioning scientific developments and the world around her. She is currently studying Chemistry, Biology, and Psychology in the DP and hopes to study Biochemistry and Cell Biology in the future. This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at www.ted.com/tedx