Asexual / Sexual Reproduction
Asexual reproduction is the process of reproducing using only one parent, effectively creating a clone of the original specimen.
Many plants and animals regularly carry out this process and it is quite common in lower creatures. Plants often produce daughter plants on runners or directly from parent leaves through asexual reproduction whilst some marine inverts such as anemones regularly 'divide' into two separate animals.
Some animals such as sponges will regenerate when damaged, if a section is removed and both sections regenerate, this also qualifies as asexual reproduction, as do cuttings taken from plants.
Sexual reproduction requires two parents and is done by the combination of gametes (cells containing the parents genetic material) to create a new organism based on a mixture of genetic information from both parents.
In the case of most higher animals, this is done by the combination of eggs and sperm but sexual reproduction can occur through a number of other methods. Because a mixture of genetic material is used, the new organism is not an exact copy of either parent, but a mixture of the two.