What are Stem Cells?
Stem cells are undifferentiated multipotent precursor cells that are capable both of perpetuating themselves as stem cells and of undergoing differentiation into one or more specialized types of cells. <http://www.bioethics.gov/reports/stemcell/glossary.html>
In other words, stem cells can be thought of as 'blank' cells that can become many different kinds of other cells and tissues of the human body.
