Stem cells research is when people in labs fertilise an egg and take some of the first few cells that are created. Those cells are general cells which can turn into a specialised cell like skin or muscle cells.

This is controversial as the embryo that the cells are taken from can be a viable embryo and can become a baby. Some people say by taking the calls you are killing a human. Some people say that it is not a human until the embryo is 80 calls thick.