Clipping parts of existing plants to propagate the plant.
Plants can also be propagated via cuttings. These cuttings can be put directly in a pot or first in water so that the cuttings can produce roots. This Pelargonium I received from a friend, and it has been in her family for several decades. In spring, I cut it back a bit and put the cuttings on water. Now, they have roots and can be planted up.