The TCM theory is esoteric and appealing but has precious little evidence to support it. It is, nevertheless, based on many years of clinical experience and observation. Some practitioners in the West have questioned the necessity of practising acupuncture exclusively as traditionally taught. Trigger point acupuncture involves inserting needles into tender points on the body, often not traditional acupuncture points. This method, however, has always been accepted in TCM which refers to them as Ah Shi points.
Periosteal acupuncture involves needling the surface of the bone.
Single point acupuncture can be used, for example PC6 on the forearm to treat nausea. 4 Segmental acupuncture is based on the distribution of the nerves and muscles in the body. Others think of 'acupuncture treatment areas', based on most of the above. Electricity can be used to stimulate the point either with electrodes attached to needles, or a laser can be used to stimulate the points. The honest answer can only be that, for the most part, we don't know.