Concepts & Principles (拳理) — the ideas behind the movement

Styles are the vehicles; this section is about the principles they all share — the ideas a practitioner of any northern art keeps running into: trained force, standing practice, the elemental theory, martial ethics, and the cultivation language of qi. These concepts usually live buried inside individual style pages; here they get their own treatment, honestly framed and cross-linked to the arts that use them.

Force and power

Jin (勁) — trained, refined force, and the taxonomy of jins (listening, neutralizing, issuing, whole-body)

Zhan Zhuang (站樁) — standing-post practice, the quiet foundation under Xingyi, Yiquan and the internal arts

The theory of the internal arts

Five Elements & Twelve Animals (五行十二形) — the elemental and animal framework that organizes Xingyi

Internal vs External (內家 / 外家) — the most argued-over distinction in Chinese martial arts

Neijia Quanfa (內家拳法) — the older 'internal boxing' of Wang Zhengnan, before Taiji took the name

Technique and conditioning

The Four Gates (踢打摔拿) — kick, strike, throw, seize: the categories every complete art must cover, including Qinna and Shuai Jiao

The Yijinjing (易筋經) — the 'sinew-changing' conditioning classic at the root of the Shaolin legend

Cultivation and ethics

Qi (氣) — what the word means in the martial context, and how to talk about it without pseudoscience

Wude (武德) — martial virtue: the ethical code, what's genuinely old in it and what's modern

See also

Northern Kung Fu Styles — the arts that put these principles to work

Source Texts — the manuals where these ideas were first written down