The process of producing more plants by seeds, cuttings, etc.
propagation refers to the process of producing more plants. The most common methods are by germinating seeds, and by creating & growing cuttings, but other methods include grafting, runners, division, and bulbs.
Use this tag for questions that refer to propagation in general - what is the best way to propagate plant X? Questions about specific methods (eg. cuttings) should use the appropriate tag for that method.