Classification of Qigong: Yin and Yang Qi and Inner and Outer Qi
Qigong, we usually vaguely think of as scams or the 'qi' in martial arts. People have an inexplicable and unwitting feeling about it. The concept of 'qi' is very blurry. So today, I'll provide a textual overview and analysis of 'qi' as I understand and have encountered it.

Qigong, meaning 'qi' as an energy practice, is essentially a process of collecting energy over time. It's divided into yin and yang qi, inner and outer qi. Let's start with outer qi, which is the 'qi' in martial arts. This type of qigong is a method of practice that combines movement, breathing, and intention to regulate. It's a process of 'leading qi with intention' and 'allowing qi to guide action.' There are two main types of this practice: 'gathering qi' and 'cultivating qi.' 'Gathering qi' can include gathering qi from the earth, the sun, streams, lakes, flowers, trees, etc. – directing intention from the baihui point to the shenmen point and then storing it in the dantian. This is 'gathering qi.' 'Gathering qi' is like harvesting crops; the collected energy needs to be utilized.
'Cultivating qi' is about directing the qi from the dantian to a specific part of the body, such as the hands, legs, or chest and back. Taking 'practicing palm techniques' as an example, intention-driven qi is directed from the dantian to the palm of the hand, practicing like hitting a sandbag. This is 'cultivating qi.' This is the practice of 'outer qi'.

Inner qi doesn't function as a breathing exercise; it's solely based on intention. It's divided into yin and yang qi. This is a skill within Taoist magic. At midnight, yang energy rises; at noon, yin energy arises. In the morning, facing the rising sun, intention-driven qi is collected, stopping at 11:00 AM. This is yang qi. In the afternoon, as the sun sets and the moon rises, facing the west, intention-driven yin qi is imported into the body. This is inner qi, or yin and yang qi. Kung fu is developed over time; when the skill has a certain amount, it can influence matter or change the properties of objects.