But hardly anybody uses the term currents. If you read the definition of Qi you may remember that the vast majority of classical metaphors used to convey the nature of Qi involve water. Picture yourself as a body of water; perhaps a river or a lake. Different parts of a river flow at different speeds and in different directions. A fish can move from one current to another quite easily having only to adjust for the difference between the speeds of the currents. Inanimate objects, like a piece of wood or a leaf or a soda can tend to stay in the same current but they also move from one current to another. They are several groups of currents and their names represent different functions or associations. They intersect with each other at various places, most are acupoints and have varying significance.
In the same manner that rivers can have more or less water in them and have their banks, course, and speed change, so the currents of Qi change size, degree of effect and even location. And, since the entire human is composed of Qi moving in different directions, feeling the point and observing the reactions of the patient are the final word on the exact location of that point on that person at that time.
These currents have their own acupoints and carry the qi through the organs and connect to all of the other currents directly. They're named for the Yin and Yang organs.
These currents are the firsts to form after conception. After birth, they act as reservoirs of Yin Qi and Jing/Essence. The Ren - Conception Vessel and the Du - Governing Vessel have acupoints but the remaining six extraordinary currents do not. They traverse the entire body from top to bottom excepting the Dai - Girdle Vessel which circles the waist.
Twelve of these currents connect with their opposite Yin or Yang Main current and then continue on a ways. Three of the the luo currents do not connect to other channels. All can act a sluice for excess Qi; local or systemic.
There are four other currents of Qi which function as suppliers to specific areas of the body. They have no acupoints and must be accessed indirectly.