This popular rail style leaves a 4” space below the bottom rail to allow for snow and debris to be swept off the deck surface. Rail posts are attached to the deck frame and support the infill sections. Rail posts need to be properly fastened and should not be spaced more than about 6 feet apart to prevent a saggy or bouncy rail.
Many builders run a 2x6 top cap continuously over the top of the posts and top rail to provide a clean finished edge and the practical purpose of providing a surface to set glasses etc. The pickets can be considerably shorter because they don’t need to be individually attached to the deck rim and they are raised off the floor. Most deck builders prefer this rail type for is simplicity and functionality above all others for wood rail construction.