How to propagate plant cuttings – Starting simple

I have always been fascinated on how anyone can make another whole plant from just a little snippet. 4th grade earth science to be exact. I am going to take us though how I save my 2 favorite coleus every year and replant many every spring. These are some unique plants that the leaves are the real show and the flowers are secondary. Another neat thing about saving the slips is I know I can have...